Science of Synthesis KnowledgeUpdates 2020/3...4.4.28.17.9 Synthesis of a-Silyl Amines from Silylmethyl Azides ..... 37 4.4.28.17.9.1 Method 1: a -Silyl Amines by Ruthenium-Catalyzed

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Science of SynthesisKnowledge Updates 2020/3

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V

Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII

Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XV

4.4.28.17 a-Silyl Alcohols, Ethers, and Amines (Update 2020)Q.-W. Zhang, K. An, and W. He . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

4.4.32.14 Allenylsilanes (Update 2020)N. Krause and N. Arisetti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5.1.3 Product Subclass 3: Metalated Germanium CompoundsC. Marschner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

5.1.13.3 Germylamines (Update 2020)C. S. Weinert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

14.4.14 2H-1-Benzopyran-2-ones (Update 2020)B. Cheng and T. Wang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

14.4.15 2H-1-Benzopyran-2-thiones (Update 2020)B. Cheng and T. Wang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

14.4.16 1H-2-Benzopyran-1-ones (Update 2020)W.-C. Gao and J. Tian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

14.4.17 3H-2-Benzopyran-3-ones (Update 2020)W.-C. Gao and J. Tian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

14.4.18 6H-Dibenzo[b,d]pyran-6-ones (Update 2020)W.-C. Gao and J. Tian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

14.4.19 9H-Xanthen-9-ones (Update 2020)W.-C. Gao and J. Tian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

14.4.20 9H-Xanthene-9-thiones (Update 2020)W.-C. Gao and J. Tian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

14.5.3 3-Oxidopyrylium Salts and Their Thio and Benzo-Fused Analogues(Update 2020)B. Jiang and C.-F. Zhu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Science of Synthesis Knowledge Updates 2020/3 Copyright © 2021 Georg Thieme Verlag KG, Stuttgart Germany. All rights reserved.

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XVI Overview

14.7.5 Benzothiopyrylium Salts (Update 2020)J.-M. Lu and L.-X. Shao . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

14.8.6 Thiopyranones and Thiopyranthiones (Update 2020)Z. Wang, T. Shi, and H.-H. Zhang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

14.10.3 Selenopyrylium and Benzoselenopyrylium Salts (Update 2020)W. Wei and X. Zhao . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435

14.12.3 Telluropyrylium and Benzotelluropyrylium Salts (Update 2020)Q. Tan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459

Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471

Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 489


http://orcid.org/0000-0002-6220-651Xhttp://orcid.org/0000-0003-4134-1779http://orcid.org/0000-0003-4118-8022

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Volume 4:Compounds of Group 15 (As, Sb, Bi) and SiliconCompounds

4.4 Product Class 4: Silicon Compounds

4.4.28.17 2020a-Silyl Alcohols, Ethers, and AminesQ.-W. Zhang, K. An, and W. He

4.4.28.17 a-Silyl Alcohols, Ethers, and Amines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

4.4.28.17.1 Carbene Insertions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

4.4.28.17.1.1 Method 1: Carbene Insertion of a-Silyl Diazoacetic Esters . . . . . . . . . . . . . . 1

4.4.28.17.1.1.1 Variation 1: a-Silyl-Substituted a-Amino Esters by Carbene Insertion intothe N-H Bond of Protected Amines . . . . . . . . . . . . . . . . . . . . . . . . 1

4.4.28.17.1.1.2 Variation 2: a-Silyl-Substituted 2-Alkoxyacetic Esters by Carbene Insertioninto the O-H Bond of Alcohols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4.4.28.17.2 Cycloaddition Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.4.28.17.2.1 Method 1: 2-Silyltetrahydrofurans or 2-Silyldihydrofurans by Three-Component Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.4.28.17.3 Reductions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4.4.28.17.3.1 Method 1: Asymmetric Reduction Using Chiral Lithium Amides . . . . . . . . . 5

4.4.28.17.3.1.1 Variation 1: a-Silyl Alcohols by Asymmetric Reduction of a,b-UnsaturatedAcylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4.4.28.17.3.1.2 Variation 2: a-Silyl Amines by Asymmetric Reduction of Silyl Imines . . . . . 6

4.4.28.17.3.2 Method 2: a-Silyl Ethers from Carbonyl Compounds by Nickel-CatalyzedDouble Silylation with 1,2-Bis(dimethylsilyl)-o-carborane . . . . 7

4.4.28.17.3.3 Method 3: Catalytic Asymmetric Hydrogenation . . . . . . . . . . . . . . . . . . . . . . . 7

4.4.28.17.3.3.1 Variation 1: a-Silyl Alcohols by Asymmetric Hydrogenation of AcylsilanesUsing Noyori’s Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.4.28.17.3.3.2 Variation 2: a-Silyl Alcohols by Asymmetric Hydrogenation of AcylsilanesUsing Tol-BINAP/(Pyridin-2-ylmethyl)amine RutheniumComplexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.4.28.17.3.3.3 Variation 3: a-Silyl Amines by Asymmetric Hydrogenation of Silylimineswith a Palladium–Bisphosphine Complex . . . . . . . . . . . . . . . . . . . 9

4.4.28.17.3.4 Method 4: a-Silyl Alcohols by Lewis Acid Promoted Reduction ofAcylsilanes Using Diethylzinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.4.28.17.4 Addition of Carbon Nucleophiles to Acylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.4.28.17.4.1 Method 1: a-Silyl Alcohols via Direct Aldol Reactions . . . . . . . . . . . . . . . . . . . 11

4.4.28.17.4.2 Method 2: Tertiary a-Silyl Alcohols from 1,3-Dienes and Acylsilanes . . . . 12

2020 Updated Section • 2020 Completely Revised Contributions • New New Contributions


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4.4.28.17.4.3 Method 3: a-Silyl Alcohols by Diethylzinc Promoted EnantioselectiveAddition of Alkynes to Acylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.4.28.17.4.4 Method 4: a-Silyl Alcohols by Rhodium-Catalyzed Arylation ofAcylsilanes Using Sodium Tetraarylborates . . . . . . . . . . . . . . . . . . 15

4.4.28.17.4.5 Method 5: a-Silyl Alcohols by Copper-Catalyzed Asymmetric Addition ofGrignard Reagents to Acylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.4.28.17.4.6 Method 6: a-Silyl Amines by Copper-Catalyzed Asymmetric Addition ofGrignard Reagents to Silyl Ketimines . . . . . . . . . . . . . . . . . . . . . . . . 16

4.4.28.17.5 Direct Addition of Silicon Nucleophiles to Carbonyl Derivatives . . . . . . . . . . . . 18

4.4.28.17.5.1 Method 1: Nucleophilic Addition of Silyllithium Reagents to CarbonylDerivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.4.28.17.5.1.1 Variation 1: a-Silyl Amines by Direct Stereoselective Addition ofSilyllithiums to Activated Imines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.4.28.17.5.1.2 Variation 2: a-Silyl Amines by Addition of Silyllithiums to IminesGenerated In Situ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.4.28.17.5.1.3 Variation 3: a-Silyl Amines by Sequential C-Si/C-C Bond Formations . . . 194.4.28.17.6 Catalytic Silylation Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.4.28.17.6.1 Method 1: a-Silyl Alcohols by Copper-Catalyzed 1,2-Addition ofNucleophilic Silicon to Aldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4.28.17.6.1.1 Variation 1: a-Silyl Alcohols by Copper-Catalyzed Enantioselective1,2-Addition of Nucleophilic Silicon to Aldehydes . . . . . . . . . . . 24

4.4.28.17.6.2 Method 2: a-Silyl Alcohols by Metal-Free Enantioselective Addition ofNucleophilic Silicon to Aromatic Aldehydes . . . . . . . . . . . . . . . . . 26

4.4.28.17.6.2.1 Variation 1: a-Silyl Alcohols by Metal-Free Enantioselective Silylation ofAromatic Aldehydes in Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.4.28.17.6.3 Method 3: a-Silyl Amines by Addition of Nucleophilic Silicon to Imines . 27

4.4.28.17.6.3.1 Variation 1: a-Silyl Amines by Copper-Catalyzed Addition of NucleophilicSilicon to Imines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.4.28.17.6.3.2 Variation 2: a-Silyl Amines by Enantioselective Addition of NucleophilicSilicon to Imines Using McQuade’s Chiral Six-MemberedN-Heterocyclic Carbene as Ligand . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.4.28.17.6.3.3 Variation 3: a-Silyl Amines by Enantioselective Addition of NucleophilicSilicon to Imines Using Hoveyda’s Chiral N-HeterocyclicCarbene as Ligand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.4.28.17.6.3.4 Variation 4: a-Silyl Amines by Enantioselective Addition of NucleophilicSilicon to Imines Using a Dihydrooxazole-Substituted CarbeneLigand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.4.28.17.6.4 Method 4: a-Silyl Amines by Conjugate Addition of Nucleophilic Silicon . 30

4.4.28.17.6.4.1 Variation 1: Chiral a-Silyl Amines by Conjugate Silylation . . . . . . . . . . . . . . . . 30

4.4.28.17.6.4.2 Variation 2: a-Silyl Amines by Enantioselective Conjugate Silyl Addition to2-Indol-1-ylacrylate Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

4.4.28.17.7 Oxidative Coupling of C-H Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.4.28.17.7.1 Method 1: a-Silyl Amines by Copper-Catalyzed Silylation of a C(sp3)-H

Bond Adjacent to an Amide Nitrogen Atom . . . . . . . . . . . . . . . . . 33



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4.4.28.17.8 Hydroamination of Vinylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.4.28.17.8.1 Method 1: a-Silyl Amines by Enantioselective Copper-CatalyzedHydroamination of Vinylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.4.28.17.8.2 Method 2: a-Amino b-Boryl Silanes by Copper-Catalyzed Aminoborationof Vinylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.4.28.17.9 Synthesis of a-Silyl Amines from Silylmethyl Azides . . . . . . . . . . . . . . . . . . . . . . . . 37

4.4.28.17.9.1 Method 1: a-Silyl Amines by Ruthenium-Catalyzed Rearrangement ofSilylmethyl Azides and Subsequent Reaction with Boronates . 37

4.4.28.17.10 Other Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.4.28.17.11 Applications of a-Silyl Alcohols, Ethers, and Amines in Organic Synthesis . . . 39

4.4.32.14 2020AllenylsilanesN. Krause and N. Arisetti

4.4.32.14 Allenylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4.4.32.14.1 Method 1: Synthesis from Lithiated Allenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4.4.32.14.1.1 Variation 1: From Allenyl Carbamates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4.4.32.14.1.2 Variation 2: From Allenamides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

4.4.32.14.1.3 Variation 3: From Silyl Enol Ethers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4.4.32.14.2 Method 2: Protodeboration of Allenylboranes . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4.4.32.14.3 Method 3: Arylation of Allenylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4.4.32.14.4 Method 4: Synthesis from Bromoallenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.4.32.14.5 Method 5: Synthesis from C-Silylated Propargylic Alcohols . . . . . . . . . . . . . 47

4.4.32.14.5.1 Variation 1: By Reduction with Schwartz’s Reagent . . . . . . . . . . . . . . . . . . . . . . 47

4.4.32.14.5.2 Variation 2: By Mitsunobu Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.4.32.14.5.3 Variation 3: By Iron-Catalyzed SN2¢ Substitution . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.4.32.14.6 Method 6: Synthesis from C-Silylated Propargylic Ethers . . . . . . . . . . . . . . . . 49

4.4.32.14.6.1 Variation 1: By Deprotonation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4.4.32.14.6.2 Variation 2: By Propargyl Claisen Rearrangement . . . . . . . . . . . . . . . . . . . . . . . . 50

4.4.32.14.6.3 Variation 3: By Friedel–Crafts Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.4.32.14.6.4 Variation 4: By Zirconium-Mediated Alkoxide Elimination and Palladium-Catalyzed Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.4.32.14.7 Method 7: Synthesis from Alkynyloxiranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.4.32.14.7.1 Variation 1: By Palladium-Catalyzed SN2¢ Substitution with Alkynes . . . . . . 54

4.4.32.14.7.2 Variation 2: By Copper-Catalyzed SN2¢ Substitution with Silylboronates . . 55

4.4.32.14.8 Method 8: Synthesis from Propargylic Carboxylates . . . . . . . . . . . . . . . . . . . . 56

4.4.32.14.8.1 Variation 1: By Palladium-Catalyzed SN2¢ Substitution . . . . . . . . . . . . . . . . . . . 56

4.4.32.14.8.2 Variation 2: By SN2¢ Substitution with Silylcuprates . . . . . . . . . . . . . . . . . . . . . . 57

4.4.32.14.8.3 Variation 3: By Gold-Catalyzed Rearrangement . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.4.32.14.9 Method 9: Synthesis from Alkynyl Lactones . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.4.32.14.10 Method 10: Synthesis from Propargylic Carbonates . . . . . . . . . . . . . . . . . . . . . 59

4.4.32.14.10.1 Variation 1: By Rhodium-Catalyzed SN2¢ Substitution with Silylboronates . 59



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4.4.32.14.10.3 Variation 3: By Copper-Mediated Reaction with Alkynes and Azides . . . . . . 61

4.4.32.14.10.4 Variation 4: By Suzuki Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.4.32.14.11 Method 11: Synthesis from Propargylic Carbamates . . . . . . . . . . . . . . . . . . . . . 62

4.4.32.14.12 Method 12: Synthesis from Propargylic Sulfinates . . . . . . . . . . . . . . . . . . . . . . . 64

4.4.32.14.13 Method 13: Synthesis from Propargylic Sulfonates . . . . . . . . . . . . . . . . . . . . . . 64

4.4.32.14.13.1 Variation 1: By Copper-Catalyzed SN2¢ Substitution . . . . . . . . . . . . . . . . . . . . . . 64

4.4.32.14.13.2 Variation 2: By Palladium-Catalyzed SN2¢ Substitution . . . . . . . . . . . . . . . . . . . 65


4.4.32.14.13.4 Variation 4: By SN2¢ Substitution with Diphenylphosphine Oxide . . . . . . . . . 67

4.4.32.14.14 Method 14: Synthesis from Propargylic Phosphates . . . . . . . . . . . . . . . . . . . . . 67

4.4.32.14.14.1 Variation 1: By Copper-Catalyzed SN2¢ Substitution with Silylboronates orSilylzinc Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

4.4.32.14.14.2 Variation 2: By Copper-Catalyzed SN2¢ Substitution with Alkylboranes . . . . 69

4.4.32.14.15 Method 15: Synthesis from Alkynylaziridines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71


4.4.32.14.15.2 Variation 2: By Reaction with Silylzinc Compounds . . . . . . . . . . . . . . . . . . . . . . 71

4.4.32.14.16 Method 16: Synthesis from Propargylic Amides . . . . . . . . . . . . . . . . . . . . . . . . . 72

4.4.32.14.17 Method 17: Synthesis from Propargylic Halides . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.4.32.14.17.1 Variation 1: By Indium-Mediated Coupling Reaction with Halosilanes . . . . 73

4.4.32.14.17.2 Variation 2: By Indium-Mediated Coupling Reaction with Aldehydes . . . . . 74

4.4.32.14.17.3 Variation 3: By Chromium-Catalyzed Coupling Reaction with Aldehydes . 74

4.4.32.14.17.4 Variation 4: By Copper-Catalyzed SN2¢ Substitution with Silylboronates orSilylzinc Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75


4.4.32.14.17.6 Variation 6: By Copper-Catalyzed SN2¢ Substitution with GrignardReagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

4.4.32.14.18 Method 18: Synthesis from Propargylic Sulfones . . . . . . . . . . . . . . . . . . . . . . . . 79

4.4.32.14.19 Method 19: Synthesis from Propargylboranes . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

4.4.32.14.19.1 Variation 1: By Protodeboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

4.4.32.14.19.2 Variation 2: By Halogenation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4.4.32.14.19.3 Variation 3: By Addition to Carbonyl Compounds . . . . . . . . . . . . . . . . . . . . . . . 82

4.4.32.14.19.4 Variation 4: By Addition to Imines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4.4.32.14.19.5 Variation 5: By Substitution Reaction with Dienyl Phosphates . . . . . . . . . . . . 86

4.4.32.14.20 Method 20: Synthesis from Propargylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.4.32.14.21 Method 21: Synthesis from Propargylstannanes . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.4.32.14.21.1 Variation 1: By Palladium-Catalyzed Reaction with Imines . . . . . . . . . . . . . . . 87

4.4.32.14.21.2 Variation 2: By Bromodestannylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.4.32.14.21.3 Variation 3: By Stille Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

4.4.32.14.22 Method 22: Synthesis from Alkynylsilanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.4.32.14.23 Method 23: Synthesis from Ynones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91



XXITable of Contents

4.4.32.14.23.1 Variation 1: By 1,4-Cuprate Addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.4.32.14.23.2 Variation 2: By Reductive Silylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.4.32.14.24 Method 24: Synthesis from Enynes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.4.32.14.24.1 Variation 1: By Hydrosilylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.4.32.14.24.2 Variation 2: By Silylboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.4.32.14.24.3 Variation 3: By Carbocupration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.4.32.14.24.4 Variation 4: By Rhodium-Catalyzed 1,6-Addition of Arylboronic Acids . . . . 94

4.4.32.14.24.5 Variation 5: By Copper-Catalyzed 1,6-Addition of Silylboronates . . . . . . . . . 95

4.4.32.14.24.6 Variation 6: By Bromolactonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

4.4.32.14.24.7 Variation 7: By Palladium-Catalyzed Hydroamination . . . . . . . . . . . . . . . . . . . . 98

4.4.32.14.24.8 Variation 8: By Copper-Catalyzed Radical Addition . . . . . . . . . . . . . . . . . . . . . . 98

4.4.32.14.24.9 Variation 9: By Copper-Catalyzed Coupling with Alkynes . . . . . . . . . . . . . . . . 99

4.4.32.14.24.10 Variation 10: By Nickel-Catalyzed Three-Component Reaction withDiorganozinc Compounds and Aldehydes . . . . . . . . . . . . . . . . . . . 99

4.4.32.14.25 Method 25: Synthesis from Dienes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

4.4.32.14.26 Method 26: Synthesis from Silylketenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

4.4.32.14.27 Method 27: Synthesis from Diazo Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . 102

4.4.32.14.27.1 Variation 1: By Reaction with Ketones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

4.4.32.14.27.2 Variation 2: By Copper-Catalyzed Coupling with Alkynes . . . . . . . . . . . . . . . . 104

4.4.32.14.28 Method 28: Synthesis from 1,1-Dihalocyclopropanes . . . . . . . . . . . . . . . . . . . . 105

4.4.32.14.29 Method 29: Synthesis from Cyclopropenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.4.32.14.29.1 Variation 1: Ring Opening by Thermal Reaction . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.4.32.14.29.2 Variation 2: Ring Opening by Platinum Catalysis . . . . . . . . . . . . . . . . . . . . . . . . 106

Volume 5:Compounds of Group 14 (Ge, Sn, Pb)

5.1 Product Class 1: Germanium Compounds

5.1.3 2020Product Subclass 3: Metalated Germanium CompoundsC. Marschner

5.1.3 Product Subclass 3: Metalated Germanium Compounds . . . . . . . . . . . . . . . . 113

5.1.3.1 Monometalated Germanium Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

5.1.3.1.1 Method 1: Cleavage of Digermanes by Reaction with Alkali Metals . . . . . 114

5.1.3.1.2 Method 2: Reduction of Germyl Halides by Reaction with Alkali Metals . 115

5.1.3.1.3 Method 3: Nucleophilic Cleavage of Digermanes, Silylgermanes, andStannylgermanes with Alkyllithiums or Alkali Metal Alkoxides 116

5.1.3.1.3.1 Variation 1: Desilylation/Hydrolysis Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

5.1.3.1.4 Method 4: Deprotonation of Germyl Hydrides Using Strong Bases . . . . . . 118

5.1.3.1.4.1 Variation 1: Deprotonation with Alkali Metal Alkyls . . . . . . . . . . . . . . . . . . . . . . 118

5.1.3.1.4.2 Variation 2: Deprotonation with Magnesium, Zinc, or Copper Bases . . . . . 120



XXII Table of Contents

5.1.3.1.5 Method 5: Transmetalation from Germylmercury Compounds UsingLithium or Magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

5.1.3.1.6 Method 6: Nucleophilic Addition to a Germylene . . . . . . . . . . . . . . . . . . . . . . 122

5.1.3.1.7 Method 7: Transmetalation by Reaction of an Alkali Metal Germanidewith a Metal Salt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

5.1.3.2 Geminal and Vicinal Dianions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

5.1.3.2.1 Method 1: Nucleophilic Abstraction of a Silyl Group from a Germanide . 125

5.1.3.2.2 Method 2: Double Deprotonation of a Germyl Dihydride . . . . . . . . . . . . . . . 125

5.1.3.2.3 Method 3: Reduction of a Masked Germylene . . . . . . . . . . . . . . . . . . . . . . . . . . 125

5.1.3.2.4 Method 4: Nucleophilic Desilylation or Degermylation with Potassiumtert-Butoxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

5.1.3.2.5 Method 5: Double Deprotonation of 1,2-Dihydrodigermanes . . . . . . . . . . . 127

5.1.13.3 2020GermylaminesC. S. Weinert

5.1.13.3 Germylamines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

5.1.13.3.1 Method 1: Synthesis of Germylamines by Metathesis of Germanium(IV)Halides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

5.1.13.3.1.1 Variation 1: Salt Metathesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

5.1.13.3.1.2 Variation 2: Metathesis Promoted by Trialkylamines . . . . . . . . . . . . . . . . . . . . . 134

5.1.13.3.2 Method 2: Synthesis of Germylamines by Ligand Exchange . . . . . . . . . . . . . 135

5.1.13.3.3 Method 3: Synthesis of Germylamines by Oxidative Addition ofGermylenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

5.1.13.3.4 Method 4: Synthesis of Germylamines Using Heterocumulenes andDoubly or Triply Bonded Carbon–Nitrogen Compounds . . . . . 136

5.1.13.3.5 Method 5: Synthesis of Macrocyclic Germylamines . . . . . . . . . . . . . . . . . . . . . 138

Volume 14:Six-Membered Hetarenes with One Chalcogen

14.4 Product Class 4: Benzopyranones and Benzopyranthiones

14.4.14 20202H-1-Benzopyran-2-onesB. Cheng and T. Wang

14.4.14 2H-1-Benzopyran-2-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

14.4.14.1 Formation of Two O-C and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14214.4.14.1.1 With Formation of the 1-8a, 1-2, 3-4, and 4-4a Bonds . . . . . . . . . . . . . . . . 14214.4.14.1.1.1 Method 1: Three-Component Coupling of Arynes, Dimethylformamide,

and Ester Enolates or Ketenimine Anions . . . . . . . . . . . . . . . . . . . . 142



XXIIITable of Contents

14.4.14.2 Formation of One O-C and Three C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14314.4.14.2.1 With Formation of the Phenyl Ring and the 1-2 and 4-4a Bonds . . . . . . . . . . 14314.4.14.2.1.1 Method 1: Trimethylsilyl Trifluoromethanesulfonate Mediated Sequential

Reaction of 2-Aryl-1-cyclopropylethanones with Allenic Esters 143

14.4.14.3 Formation of One O-C and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14414.4.14.3.1 With Formation of the 1-2, 2-3, and 3-4 Bonds . . . . . . . . . . . . . . . . . . . . . . . . 14414.4.14.3.1.1 Method 1: Carbonylation of 2-Hydroxybenzaldehydes and Benzyl

Chlorides Followed by Intramolecular Condensation . . . . . . . . . 144

14.4.14.3.2 With Formation of the 1-2, 2-3, and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . 14514.4.14.3.2.1 Method 1: Carbonylative Annulation of Internal Alkynes Catalyzed by

Cobalt/Rhodium Nanoparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

14.4.14.3.2.2 Method 2: Palladium-Catalyzed Oxidative Carbonylation ofNonpreactivated Phenols and Terminal Alkynes . . . . . . . . . . . . . 146

14.4.14.4 Formation of One O-C and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14714.4.14.4.1 With Formation of the 1-2 and 2-3 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14714.4.14.4.1.1 Method 1: Palladium-Catalyzed Dicarbonylation . . . . . . . . . . . . . . . . . . . . . . . 147

14.4.14.4.1.2 Method 2: Palladium-Catalyzed C-H Activation/Carbonylation of2-(2-Hydroxyphenyl)-4H-1-benzopyran-4-ones . . . . . . . . . . . . . . 148

14.4.14.4.1.3 Method 3: Cyclocarbonylation of 2-Alkenylphenols . . . . . . . . . . . . . . . . . . . . . 148

14.4.14.4.1.3.1 Variation 1: Cyclocarbonylation with Carbon Monoxide Catalyzed byPalladium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

14.4.14.4.1.3.2 Variation 2: Palladium-Catalyzed Cyclocarbonylation with Carbon Dioxide 150

14.4.14.4.1.3.3 Variation 3: Cyclocarbonylation with Carbon Monoxide Catalyzed by(h5-Pentamethylcyclopentadienyl)cobalt(III) . . . . . . . . . . . . . . . . 151

14.4.14.4.1.3.4 Variation 4: Cyclocarbonylation with Carbon Monoxide Catalyzed byRhodium(III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

14.4.14.4.1.3.5 Variation 5: Cyclocarbonylation with Carbon Dioxide under Transition-Metal-Free Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

14.4.14.4.2 With Formation of the 1-2 and 3-4 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15414.4.14.4.2.1 Method 1: Esterification Followed by Intramolecular Condensation . . . . . 154

14.4.14.4.2.1.1 Variation 1: Mukaiyama’s Esterification Protocol . . . . . . . . . . . . . . . . . . . . . . . . 154

14.4.14.4.2.1.2 Variation 2: Using Dicyclohexylcarbodiimide as Coupling Reagent . . . . . . . 154

14.4.14.4.2.1.3 Variation 3: Using Cyanuric Chloride as Coupling Reagent . . . . . . . . . . . . . . . 155

14.4.14.4.2.1.4 Variation 4: Perkin Condensation Mediated by PropylphosphonicAnhydride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

14.4.14.4.2.2 Method 2: Annulation of 2-Hydroxybenzaldehyde Derivatives andMalonic Acid Half-Thioesters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

14.4.14.4.2.3 Method 3: Ultrasound-Assisted Solvent-Free Parallel Synthesis UsingN-Acylbenzotriazoles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

14.4.14.4.2.4 Method 4: Knoevenagel Condensation of Meldrum’s Acid with2-Hydroxybenzaldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

14.4.14.4.2.5 Method 5: Annulation of a-Aroyl Ketene S,S-Acetals and2-Hydroxybenzaldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161



XXIV Table of Contents

14.4.14.4.2.5.1 Variation 1: Piperidine as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

14.4.14.4.2.5.2 Variation 2: Indium(III) Chloride as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

14.4.14.4.2.5.3 Variation 3: Copper(II) Bromide or Hydrogen Bromide as Catalyst . . . . . . . . 163

14.4.14.4.2.6 Method 6: Annulation of 2-Hydroxybenzaldehyde and (Het)Aryl-Substituted 1,1-Dibromoalk-1-enes . . . . . . . . . . . . . . . . . . . . . . . . . 164

14.4.14.4.2.7 Method 7: Annulation of 2-Hydroxybenzaldehydes with Acetylenic EstersUsing Combined Catalysis of Piperidine and Lewis Acid . . . . . . 165

14.4.14.4.2.8 Method 8: Organocatalytic Condensation/Ring-Opening/AnnulationCascade Reactions between N-(tert-Butoxycarbonyl)indolin-2-ones or Benzofuran-2(3H)-ones and2-Hydroxybenzaldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

14.4.14.4.2.9 Method 9: Iron(III) Chloride Promoted Cascade Reaction ofPropargylamines with b-Oxo Esters . . . . . . . . . . . . . . . . . . . . . . . . . 168

14.4.14.4.2.10 Method 10: Carbocation-Initiated [4 + 2] Cycloaddition . . . . . . . . . . . . . . . . . . 169

14.4.14.4.2.11 Method 11: Multicomponent Reaction of tert-Butyl Isocyanide, DialkylAcetylenedicarboxylates, and 2-Hydroxybenzaldehydes . . . . . 170

14.4.14.4.2.12 Method 12: Triphenylphosphine-Catalyzed Annulation of Aldimine Estersand b¢-Acetoxy Allenoates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

14.4.14.4.2.13 Method 13: Rhodium-Catalyzed Annulation of Aldehydes with Alkynes . . 172

14.4.14.4.2.14 Method 14: Annulation via Isomerizative Condensation Reaction ofa,b-Unsaturated Carboxylic Acid Chlorides . . . . . . . . . . . . . . . . . 172

14.4.14.4.2.15 Method 15: N-Heterocyclic Carbene Catalyzed Domino RedoxEsterification/Cyclization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

14.4.14.4.2.16 Method 16: Copper-Catalyzed Oxidative Annulation of2-Hydroxybenzaldehyde Hydrazones and Terminal Alkynes . . 174

14.4.14.4.2.17 Method 17: N-Heterocyclic Carbene Catalyzed Annulation of Enalswith (E)-1-(2-Hydroxyphenyl)prop-2-en-1-ones . . . . . . . . . . . . . . 175

14.4.14.4.3 With Formation of the 1-2 and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17614.4.14.4.3.1 Method 1: Pechmann Reaction of Phenols and b-Oxo Esters . . . . . . . . . . . . 176

14.4.14.4.3.1.1 Variation 1: Wells–Dawson Heteropolyacid as Catalyst . . . . . . . . . . . . . . . . . . 177

14.4.14.4.3.1.2 Variation 2: Zirconium(IV) Chloride as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . 177

14.4.14.4.3.1.3 Variation 3: Ammonium Cerium(IV) Nitrate as Catalyst . . . . . . . . . . . . . . . . . . 178

14.4.14.4.3.1.4 Variation 4: Sulfamic Acid as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

14.4.14.4.3.1.5 Variation 5: Samarium(III) Nitrate Hexahydrate as Catalyst . . . . . . . . . . . . . . 181

14.4.14.4.3.1.6 Variation 6: Bismuth(III) Chloride as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

14.4.14.4.3.1.7 Variation 7: Gallium(III) Iodide as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

14.4.14.4.3.1.8 Variation 8: Bismuth(III) Nitrate Pentahydrate as Catalyst . . . . . . . . . . . . . . . . 183

14.4.14.4.3.1.9 Variation 9: Zirconyl Chloride Octahydrate as Catalyst . . . . . . . . . . . . . . . . . . . 184

14.4.14.4.3.1.10 Variation 10: Scandium(III) Trifluoromethanesulfonate as Catalyst . . . . . . . . 185

14.4.14.4.3.1.11 Variation 11: Molecular Iodine or Silver(I) Trifluoromethanesulfonate asCatalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

14.4.14.4.3.1.12 Variation 12: Sulfated Zirconia as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

14.4.14.4.3.1.13 Variation 13: Oxalic Acid as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

14.4.14.4.3.1.14 Variation 14: Titanium-Doped Zinc(II) Oxide Nanoparticles as Catalyst . . . . 188



XXVTable of Contents

14.4.14.4.3.2 Method 2: Ytterbium(III) Trifluoromethanesulfonate CatalyzedAnnulation of Phenols with 5-Alkylidene-SubstitutedMeldrum’s Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

14.4.14.4.3.3 Method 3: Palladium-Catalyzed Heck Lactonization Reaction . . . . . . . . . . . 191

14.4.14.4.3.4 Method 4: Hydroarylation/Lactonization Annulation of Phenols andAlk-2-ynoic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

14.4.14.4.3.4.1 Variation 1: Palladium(II) Acetate Catalyzed Hydroarylation . . . . . . . . . . . . . 191

14.4.14.4.3.4.2 Variation 2: Ytterbium(III) Trifluoromethanesulfonate PromotedHydroarylation Using Microwave Irradiation . . . . . . . . . . . . . . . . . 192

14.4.14.4.3.5 Method 5: Hydroarylation/Annulation of Phenols and Alkynoate Esters . 193

14.4.14.4.3.5.1 Variation 1: The Combination of a Palladium Complex and Formic Acid asCatalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

14.4.14.4.3.5.2 Variation 2: Zinc(II) Chloride as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

14.4.14.4.3.5.3 Variation 3: Without a Catalyst in Refluxing Water . . . . . . . . . . . . . . . . . . . . . . 195

14.4.14.4.3.6 Method 6: Condensation of Malic Acid and Phenols under MicrowaveIrradiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

14.4.14.4.3.7 Method 7: Brønsted Acid Mediated Condensation of Allenes withSubstituted Phenols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

14.4.14.4.3.8 Method 8: Claisen Rearrangement/Lactonization/IsomerizationSequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

14.4.14.4.3.8.1 Variation 1: Solid State Melt Claisen Rearrangement Reaction . . . . . . . . . . . 197

14.4.14.4.3.8.2 Variation 2: N,N-Diethylaniline-Promoted Claisen Rearrangement underReflux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

14.4.14.5 Formation of One O-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19914.4.14.5.1 With Formation of the 1-2 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19914.4.14.5.1.1 Method 1: Arylation/Lactonization of 3-(2-Hydroxyphenyl)acrylates . . . . 199

14.4.14.5.1.1.1 Variation 1: Palladium-Mediated Heck/Lactonization Reaction with ArylHalides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

14.4.14.5.1.1.2 Variation 2: Palladium-Catalyzed Arylation/Cyclization withDiaryliodonium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

14.4.14.5.1.2 Method 2: Visible-Light-Driven Fluoroalkylation/Lactonization . . . . . . . . . . 201

14.4.14.5.1.3 Method 3: Iodine-Promoted Diiodination/Lactonization . . . . . . . . . . . . . . . . 202

14.4.14.5.1.4 Method 4: Copper(I) Acetate Catalyzed Arylation/Cyclization withArylboronic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

14.4.14.5.1.5 Method 5: N-Heterocyclic Carbene Catalyzed Redox Lactonization of3-(2-Hydroxyaryl)acrylaldehydes and 2-(3-Hydroxyprop-1-enyl)phenols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

14.4.14.5.2 With Formation of the 1-8a Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20514.4.14.5.2.1 Method 1: (Diacetoxyiodo)benzene/Molecular Iodine Mediated

Oxidative Cyclization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

14.4.14.5.2.2 Method 2: Cyclization Mediated by In Situ Generated Iodine(III) Reagents 206

14.4.14.5.2.3 Method 3: Isomerization/Cyclization Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . 206

14.4.14.5.2.4 Method 4: Visible-Light-Mediated Annulation . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.4.14.5.2.5 Method 5: Electrochemical Dehydrogenative Lactonization . . . . . . . . . . . . 207



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14.4.14.6 Formation of One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20814.4.14.6.1 With Formation of the 3-4 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20814.4.14.6.1.1 Method 1: Consecutive a- and b-Activation of

3-(Trimethylsilyl)propynoates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

14.4.14.6.1.2 Method 2: Tellurium-Triggered Cyclization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

14.4.14.6.1.3 Method 3: Palladium-Mediated Annulation with Arylboronic Acids . . . . . 211

14.4.14.6.1.4 Method 4: Phosphine-Mediated Domino Annulation . . . . . . . . . . . . . . . . . . . 211

14.4.14.6.2 With Formation of the 4-4a Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21314.4.14.6.2.1 Method 1: Friedel–Crafts Alkenylation of Aryl Alkynoates . . . . . . . . . . . . . . 213

14.4.14.6.2.1.1 Variation 1: Hafnium(IV) Trifluoromethanesulfonate as Catalyst with theAssistance of Ionic Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

14.4.14.6.2.1.2 Variation 2: Gold(III) as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

14.4.14.6.2.1.3 Variation 3: Iron(III) Chloride as Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

14.4.14.6.2.2 Method 2: Radical-Initiated Annulation of Aryl Alkynoates . . . . . . . . . . . . . 215

14.4.14.6.2.2.1 Variation 1: Radical Annulation with Solvent as Radical Sources . . . . . . . . . . 215

14.4.14.6.2.2.2 Variation 2: Radical Annulation with In Situ Generated AlkylsulfonylRadicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

14.4.14.6.2.2.3 Variation 3: Light-Mediated Radical Annulation with N-Iodosuccinimide . . 217

14.4.14.6.2.2.4 Variation 4: Visible-Light-Induced Radical Annulation with Assistance ofDiethyl Bromomalonate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

14.4.14.6.2.2.5 Variation 5: Electrochemical Oxidative Annulation with Diselenides orDisulfides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

14.4.14.6.2.2.6 Variation 6: tert-Butyl Hydroperoxide Initiated Radical Annulation withDiselenides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

14.4.14.6.2.2.7 Variation 7: Copper-Catalyzed Radical Annulation with Togni’s Reagent . . 222

14.4.14.6.2.2.8 Variation 8: Silver-Mediated Radical Annulation of a-Oxo Acids . . . . . . . . . . 223

14.4.14.6.2.2.9 Variation 9: Iron(III) Chloride Mediated Annulation with Diselenides . . . . . 225

14.4.14.7 Aromatization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

14.4.14.7.1 Formal Aromatization Resulting from Tautomerism . . . . . . . . . . . . . . . . . . . . . . . . 226

14.4.14.7.1.1 Method 1: Rhodium(II)-Catalyzed Decomposition of 3-Diazo-1-benzopyran-2,4-dione . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

14.4.14.7.1.2 Method 2: Rearrangement of Spiro-3,4-dihydro-2H-1-benzopyran-2-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

14.4.14.7.1.3 Method 3: Michael–Oxa-Michael–Aromatization . . . . . . . . . . . . . . . . . . . . . . . 228

14.4.14.7.1.4 Method 4: Copper/Selectfluor Mediated Dehydration–Oxidation ofTertiary Cyclic Alcohols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228



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14.4.15 20202H-1-Benzopyran-2-thionesB. Cheng and T. Wang

14.4.15 2H-1-Benzopyran-2-thiones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

14.4.15.1 Formation of One C-O and One C-C Bond: Formation of the 1-2 and 2-3Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

14.4.15.1.1 Method 1: Annulation of Benzyl 2-Hydroxyphenyl Ketones with CarbonDisulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

14.4.15.2 Formation of One C-O and One C-C Bond: Formation of the 1-2 and 3-4Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

14.4.15.2.1 Method 1: Annulation of b-Oxo Dithioesters and2-Hydroxybenzaldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

14.4.15.2.1.1 Variation 1: Catalyzed by Tin(II) Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

14.4.15.2.1.2 Variation 2: Catalyzed by Piperidine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

14.4.15.2.1.3 Variation 3: Catalyzed by Silica Sulfuric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

14.4.15.2.1.4 Variation 4: Catalyzed by Indium(III) Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

14.4.15.3 Formation of One C-O and One C-C Bond: Formation of the 1-2 and 4-4aBonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

14.4.15.3.1 Method 1: Aluminum Trichloride Catalyzed Pechmann Condensation . . . 239

14.4.16 20201H-2-Benzopyran-1-onesW.-C. Gao and J. Tian


14.4.16.1 Synthesis by Ring-Closure Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

14.4.16.1.1 By Annulation to an Arene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

14.4.16.1.1.1 By Formation of One O-C and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24114.4.16.1.1.1.1 With Formation of the 1-2 and 3-4 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24114.4.16.1.1.1.1.1 Method 1: Cyclocondensation of (2-Carboxymethyl)benzoic Acids with

Propanoates or Acrylates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

14.4.16.1.1.1.2 With Formation of the 1-2 and 1-8a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24214.4.16.1.1.1.2.1 Method 1: Carbonylative Cyclization of 2-Bromobenzyl Ketones Using

Phenyl Formate as Carbonyl Source . . . . . . . . . . . . . . . . . . . . . . . . . 242

14.4.16.1.1.1.2.2 Method 2: Carbonylative Cyclization of 2-Bromobenzyl Ketones Usingtert-Butyl Isocyanide as Carbonyl Source . . . . . . . . . . . . . . . . . . . . 243

14.4.16.1.1.1.3 With Formation of the 2-3 and 3-4 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24414.4.16.1.1.1.3.1 Method 1: Synthesis from 2-Benzoyl- or 2-Formylbenzoates and

a-Diazophosphonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

14.4.16.1.1.1.4 With Formation of the 2-3 and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24614.4.16.1.1.1.4.1 Method 1: Cyclization of Benzoic Acids with Alkynes . . . . . . . . . . . . . . . . . . . 246

14.4.16.1.1.1.4.2 Method 2: Cyclization of tert-Butyl Peroxybenzoates with Alkynes . . . . . . 246

14.4.16.1.1.1.4.3 Method 3: Cyclization of O-Benzoylhydroxylamines with Alkynes . . . . . . . 248



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14.4.16.1.1.1.5 With Formation of the 1-2 and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24814.4.16.1.1.1.5.1 Method 1: Cyclization of 2-Halobenzoates with b-Hydroxy Ketones . . . . . 249

14.4.16.1.1.1.5.1.1 Variation 1: Intermolecular Substitution of 2-Iodobenzoic Acid with1,3-Diketones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

14.4.16.1.1.1.5.1.2 Variation 2: Cyclization of 2-Halobenzoates with Unactivated Ketones . . . 250

14.4.16.1.1.1.5.2 Method 2: Cyclization of Benzamides and Diazo Compounds . . . . . . . . . . . 251

14.4.16.1.1.1.5.3 Method 3: Palladium-Catalyzed Intermolecular Acylation of 2-Aryl-2-diazoacetates with 2-Bromobenzaldehydes . . . . . . . . . . . . . . . 252

14.4.16.1.1.2 By Formation of One C-O Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25414.4.16.1.1.2.1 With Formation of the 1-2 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25414.4.16.1.1.2.1.1 Method 1: Cyclization of 2-(2-Oxoalkyl)benzaldehydes . . . . . . . . . . . . . . . . . 254

14.4.16.1.1.2.2 With Formation of the 2-3 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25514.4.16.1.1.2.2.1 Method 1: Cyclization of 2-(Carboxymethyl)benzoic Acid with

Phosphoryl Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

14.4.16.1.1.2.2.2 Method 2: Cyclization of 2-(Carboxymethyl)benzoic Acids withPhosphorus Pentachloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

14.4.16.1.1.3 By Formation of One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25614.4.16.1.1.3.1 With Formation of the 4-4a Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25614.4.16.1.1.3.1.1 Method 1: Silver(I)-Mediated Annulation of Enol Esters . . . . . . . . . . . . . . . . . 256

14.4.16.2 Aromatization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

14.4.16.2.1 Method 1: Elimination of Methanesulfinic Acid . . . . . . . . . . . . . . . . . . . . . . . . . 257

14.4.16.3 Synthesis by Substituent Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

14.4.16.3.1 Substitution of Existing Substituents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

14.4.16.3.1.1 Of Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

14.4.16.3.1.1.1 Method 1: Oxidation of 1-Benzylidene-1H-2-benzopyrans with3-Chloroperoxybenzoic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

14.4.16.3.1.2 Of Halogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

14.4.16.3.1.2.1 Method 1: Cross Coupling of 3-Chloro-1H-2-benzopyran-1-one . . . . . . . . . 259

14.4.17 20203H-2-Benzopyran-3-onesW.-C. Gao and J. Tian



14.4.17.1.1 By Formation of One O-C Bond and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . 26114.4.17.1.1.1 Method 1: Pechmann Reaction/Friedel–Crafts Reaction of 2-Naphthols

with Acetone-1,3-dicarboxylates . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

14.4.17.2 Synthesis by Ring Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

14.4.17.2.1 By Ring Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

14.4.17.2.1.1 Method 1: Rearrangement of 1,3-Diphenyl-2H-cyclopenta[l]phenanthren-2-one . . . . . . . . . . . . . . . . . . . . . . . . . . . 262



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14.4.18 20206H-Dibenzo[b,d]pyran-6-onesW.-C. Gao and J. Tian

14.4.18 6H-Dibenzo[b,d]pyran-6-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265



14.4.18.1.1.1 By Formation of One O-C and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26514.4.18.1.1.1.1 With Formation of the 5-6 and 10a-10b Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . 26514.4.18.1.1.1.1.1 Method 1: Copper-Mediated Condensation of 2-Halobenzoic Acids with

Resorcinols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

14.4.18.1.1.1.1.2 Method 2: Suzuki–Miyaura Cross Coupling of (2-Hydroxyaryl)boronicAcids with 2-Bromobenzoates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

14.4.18.1.1.1.2 With Formation of the 4a-5 and 10a-10b Bonds . . . . . . . . . . . . . . . . . . . . . . . . . 26814.4.18.1.1.1.2.1 Method 1: Palladium-Catalyzed Decarboxylative Cross Coupling and

Lactonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268

14.4.18.1.1.1.3 With Formation of the 5-6 and 6-6a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26914.4.18.1.1.1.3.1 Method 1: Palladium-Catalyzed Directed C-H Activation/Carbonylation

of Biphenyl-2-ols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

14.4.18.1.1.2 By Formation of One O-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27114.4.18.1.1.2.1 With Formation of the 4a-5 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27114.4.18.1.1.2.1.1 Method 1: Palladium-Catalyzed C-H Lactonization of Biphenyl-

2-carboxylic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

14.4.18.1.1.2.1.2 Method 2: Aryl Iodide Catalyzed C-H Lactonization of Biphenyl-2-carboxylic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

14.4.18.1.1.2.1.3 Method 3: Cyclization of 2¢-Halobiaryl-2-carboxylates . . . . . . . . . . . . . . . . . . 273

14.4.18.1.1.2.2 With Formation of the 5-6 Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27514.4.18.1.1.2.2.1 Method 1: Lactonization of a Methyl Ester with a Phenolic Hydroxy

Group after Benzyl Ether Deprotection . . . . . . . . . . . . . . . . . . . . . . 275

14.4.18.1.1.3 By Formation of One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27514.4.18.1.1.3.1 With Formation of the 10a-10b Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27514.4.18.1.1.3.1.1 Method 1: Rhodium-Catalyzed Cyclization of Aryl 3-Diazo-

4-oxonaphthalene-2-carboxylates . . . . . . . . . . . . . . . . . . . . . . . . . . 275

14.4.18.1.1.4 By Formation of Two O-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27714.4.18.1.1.4.1 With Formation of the 5-4a and 5-6 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27714.4.18.1.1.4.1.1 Method 1: Cyclization of Biphenyl-2-carbaldehydes . . . . . . . . . . . . . . . . . . . . 277

14.4.18.1.2 By Annulation to a Heterocycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

14.4.18.1.2.1 By Formation of One C-O Bond and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . 27814.4.18.1.2.1.1 With Formation of the 1-2, 10b-4a, and 5-6 Bonds . . . . . . . . . . . . . . . . . . . . . 27814.4.18.1.2.1.1.1 Method 1: Extension of the Hauser–Kraus Annulation . . . . . . . . . . . . . . . . . . 278

14.4.18.1.2.2 By Formation of Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27814.4.18.1.2.2.1 With Formation of the 6a-7 and 10-10a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . 278



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14.4.18.1.2.2.1.1 Method 1: Synthesis of 6H-Dibenzo[b,d]pyran-6-ones from 3,4-Dichloro-2H-1-benzopyran-2-ones and Buta-1,3-dienes . . . . . . . . . . . . . . 278

14.4.18.1.2.2.2 With Formation of the 6a-7 and 8-9 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28114.4.18.1.2.2.2.1 Method 1: Diels–Alder Cycloaddition of 4-(1-Butoxyvinyl)- or

4-(2-Butoxyvinyl)-2H-1-benzopyran-2-ones with Dienophiles . 281

14.4.18.1.2.2.2.2 Method 2: Intramolecular Diels–Alder Cycloaddition . . . . . . . . . . . . . . . . . . . 282

14.4.18.2 Synthesis by Ring Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

14.4.18.2.1 Rearrangement/Annulation of 4-(2,2-Diarylvinylidene)-3,4-dihydro-1H-2-benzopyran-1-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

14.4.18.2.1.1 Method 1: Tandem C-O Bond Cleavage/6p-Electrocyclization/OxidativeAromatization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

14.4.19 20209H-Xanthen-9-onesW.-C. Gao and J. Tian

14.4.19 9H-Xanthen-9-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289



14.4.19.1.1.1 By Formation of One O-C and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28914.4.19.1.1.1.1 With Formation of the 4a-10 and 9-9a, the 8a-9 and 10-10a, the 4a-10

and 8a-9, or the 9-9a and 10-10a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28914.4.19.1.1.1.1.1 Method 1: Etherification/Acylation of Diaryliodonium Salts with

2-Hydroxybenzoates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

14.4.19.1.1.1.1.2 Method 2: Etherification/Acylation of Benzynes with2-Hydroxybenzoates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

14.4.19.1.1.1.1.3 Method 3: Palladium-Catalyzed Acylation/SNAr Sequence of 1-Bromo-2-fluorobenzenes and 2-Hydroxybenzaldehydes . . . . . . . . . . . . . 292

14.4.19.1.1.2 By Formation of Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29414.4.19.1.1.2.1 With Formation of the 8a-9 and 9-9a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29414.4.19.1.1.2.1.1 Method 1: Palladium-Catalyzed Oxidative Carbonylation of Diaryl Ethers 294

14.4.19.1.1.2.1.2 Method 2: Palladium-Catalyzed Oxidative Carbonylation of2-(Aryloxy)benzenediazonium Tetrafluoroborates . . . . . . . . . . . 295

14.4.19.1.1.2.1.3 Method 3: Palladium-Catalyzed Oxidative Carbonylation of Aryl2-Iodoaryl Ethers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

14.4.19.1.2 By Annulation to a Heterocycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

14.4.19.1.2.1 By Formation of Three C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29714.4.19.1.2.1.1 With Formation of the 5-10a, 6-7, and 8-8a Bonds . . . . . . . . . . . . . . . . . . . . . 29714.4.19.1.2.1.1.1 Method 1: Palladium-Catalyzed Cascade Reactions of 3-Iodo-4H-

1-benzopyran-4-ones with Aryl Iodides and Norbornadiene . . 297

14.4.19.1.2.1.2 With Formation of the 1-2, 3-4, and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . 30014.4.19.1.2.1.2.1 Method 1: Multicomponent Reaction with Methyl 2-Oxo-2-(4-oxo-4H-

1-benzopyran-3-yl)acetates, Isocyanides, and Dienophiles . . . 300



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14.4.19.1.2.1.2.2 Method 2: Multicomponent Reaction with 4-Oxo-4H-1-benzopyran-3-carbaldehydes and N-Tosylhydrazones . . . . . . . . . . . . . . . . . . . . 301

14.4.19.1.2.1.3 With Formation of the 1-2, 3-4, and 1¢-2¢ Bonds . . . . . . . . . . . . . . . . . . . . . . . 30314.4.19.1.2.1.3.1 Method 1: Tandem Reaction of 3-(Alk-1-ynyl)-2-methyl-4H-

1-benzopyran-4-ones with Ethyl (E)-3-(4-Oxo-4H-1-benzopyran-3-yl)acrylate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304

14.4.19.1.2.1.3.2 Method 2: Tandem Reaction of 3-Acetyl-2-methyl-4H-1-benzopyran-4-one with 3-Vinylic 4H-1-Benzopyran-4-ones . . . . . . . . . . . . . . . 305

14.4.19.1.2.1.4 With Formation of the 1-9a, 2-3, and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . 30614.4.19.1.2.1.4.1 Method 1: Palladium-Catalyzed Multicomponent Coupling Reaction . . . . 306

14.4.19.1.2.2 By Formation of Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30714.4.19.1.2.2.1 With Formation of the 5-6 and 7-8 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30714.4.19.1.2.2.1.1 Method 1: Tandem Reaction of 3-(Alk-1-ynyl)-4H-1-benzopyran-4-ones

with 1,3-Dicarbonyls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

14.4.19.1.2.2.1.2 Method 2: Tandem Reaction of 3-(Alk-1-ynyl)-4H-1-benzopyran-4-oneswith Acetonitriles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

14.4.19.1.2.2.2 With Formation of the 2-3 and 1-9a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31114.4.19.1.2.2.2.1 Method 1: Cyclization of 2-Aryl-3-iodo-4H-1-benzopyran-4-ones with

Electron-Rich Five-Membered Hetarenes . . . . . . . . . . . . . . . . . . . . 311

14.4.19.1.2.2.2.2 Method 2: Dimerization of 3-Substituted 4H-1-Benzopyran-4-ones . . . . . 312

14.4.19.1.2.2.2.2.1 Variation 1: Dimerization of 3-(Alk-1-ynyl)-4H-1-benzopyran-4-ones . . . . . 312

14.4.19.1.2.2.2.2.2 Variation 2: Dimerization of 5,6-Dehydropolivione . . . . . . . . . . . . . . . . . . . . . . 313

14.4.19.1.2.2.3 With Formation of the 2-3 and 4-4a Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31414.4.19.1.2.2.3.1 Method 1: Inverse-Electron-Demand Diels–Alder Reaction . . . . . . . . . . . . . 314

14.4.19.1.2.2.4 With Formation of the 1-9a and 2-3 Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31614.4.19.1.2.2.4.1 Method 1: Tandem Diels–Alder/Aromatization of 2-Vinylic

4H-1-Benzopyran-4-ones with Benzynes . . . . . . . . . . . . . . . . . . . . 316

14.4.19.1.2.3 By Formation of Two C-C Bonds and one C-O Bond . . . . . . . . . . . . . . . . . . . . . . 31714.4.19.1.2.3.1 With Formation of the 1-9a, 3-4, and 10-10a Bonds . . . . . . . . . . . . . . . . . . . . 31714.4.19.1.2.3.1.1 Method 1: Tandem Reactions of ortho-Substituted Arylpropynones and

b-Dicarbonyls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

14.4.19.1.2.4 By Formation of One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31814.4.19.1.2.4.1 With Formation of the 1-9a Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31814.4.19.1.2.4.1.1 Method 1: Electrocyclization/Oxidation of 2-Dienyl-4H-1-benzopyran-

4-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318



14.4.19.2.1.1 Of Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

14.4.19.2.1.1.1 Visible-Light-Induced Aerobic Oxidation of 9H-Xanthenes . . . . . . . . . . . . . . . . . . 319

14.4.19.2.1.2 Of Iodine and Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320



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14.4.19.2.1.2.1 Method 1: Oxidation of Cyclic DiphenyliodoniumTrifluoromethanesulfonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320

14.4.20 20209H-Xanthene-9-thionesW.-C. Gao and J. Tian

14.4.20 9H-Xanthene-9-thiones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323



14.4.20.1.1.1 Of Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

14.4.20.1.1.1.1 Method 1: Reaction of Elemental Sulfur with a Carbene Precursor . . . . . . 323

14.4.20.1.1.2 Of Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324

14.4.20.1.1.2.1 Method 1: Microwave-Assisted Thionation with a ThiophosphorylChloride/Water/Triethylamine System . . . . . . . . . . . . . . . . . . . . . . 324

14.5 Product Class 5: 3-Oxidopyrylium Salts and Their Thio and Benzo-FusedAnalogues

14.5.3 20203-Oxidopyrylium Salts and Their Thio and Benzo-FusedAnaloguesB. Jiang and C.-F. Zhu

14.5.3 3-Oxidopyrylium Salts and Their Thio and Benzo-Fused Analogues . . . . . 327

14.5.3.1 Synthesis of 3-Oxidopyrylium Salts and Their Thio and Benzo-FusedAnalogues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

14.5.3.1.1 Method 1: Cyclodehydration of 2-Acetyl-3-(N-arylacetamido)benzo[b]furans, and -benzo[b]thiophenes . . . . 327

14.5.3.1.2 Method 2: Aldol-Type Condensation of Hydroxybenzaldehydes and2-Oxygen-Substituted 1-Phenylethanones . . . . . . . . . . . . . . . . . . 329

14.5.3.1.3 Method 3: Biomimetic Oxidation Route to Anthocyanins . . . . . . . . . . . . . . . 331

14.5.3.1.4 Method 4: Reductive Synthesis of Anthocyanidins Using LithiumAluminum Hydride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

14.5.3.1.5 Method 5: In Situ Generation of 3-Oxidopyrylium Salts from3-Hydroxypyran-4-ones Using Sulfonic Acids . . . . . . . . . . . . . . . . 333

14.5.3.2 Applications of 3-Oxidopyrylium Salts and Their Thio and Benzo-FusedAnalogues in Organic Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

14.5.3.2.1 Method 1: [3 + 2]-Cycloaddition Reactions of 3-Hydroxypyrylium Salts . . 334

14.5.3.2.2 Method 2: [3 + 2]-Cycloaddition Reactions with In Situ Generation of the3-Oxidopyrylium Salt from 6-Acetoxydihydropyran-3-one . . . 336

14.5.3.2.3 Method 3: Condensation between Aroylacetones and PhloroglucinolDihydrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337



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14.7 Product Class 7: Benzothiopyrylium Salts

14.7.5 2020Benzothiopyrylium SaltsJ.-M. Lu and L.-X. Shao

14.7.5 Benzothiopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

14.7.5.1 1-Benzothiopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342

14.7.5.1.1 Synthesis by Ring-Closure Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342

14.7.5.1.1.1 By Annulation to an Arene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342

14.7.5.1.1.1.1 By Formation of One S-C and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34214.7.5.1.1.1.1.1 Method 1: Cyclization of Benzenethiols with b-Oxo Esters . . . . . . . . . . . . . . 342

14.7.5.1.2 Synthesis by Substituent Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

14.7.5.1.2.1 Of a Methyl Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

14.7.5.1.2.1.1 Method 1: Reaction with Benzaldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

14.7.5.1.2.1.2 Method 2: Reaction with N-[3-(Phenylimino)prop-1-enyl]benzenaminium Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349

14.7.5.2 2-Benzothiopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351


14.7.5.2.1.1 Method 1: Cyclization of Bis[(arylmethyl)sulfanyl]acetylenes with IodineMonochloride or Molecular Bromine . . . . . . . . . . . . . . . . . . . . . . . . 351

14.7.5.2.1.2 Method 2: Cyclization of 2-(Alk-1-ynyl)benzothioamides . . . . . . . . . . . . . . . 355

14.7.5.3 Dibenzo[b,e]thiopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355


14.7.5.3.1.1 By Formation of Two S-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35614.7.5.3.1.1.1 Method 1: Synthesis from Diarylmethane and Sulfur . . . . . . . . . . . . . . . . . . . 356

14.7.5.3.1.2 By Formation of Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35714.7.5.3.1.2.1 Method 1: Condensation of Diaryl Sulfides and Benzaldehyde . . . . . . . . . . 357

14.7.5.3.1.2.2 Method 2: Synthesis from Diaryl Sulfides and Acid Chlorides . . . . . . . . . . . 358

14.7.5.3.1.2.3 Method 3: Synthesis from Diaryl Sulfides and Chloroformate . . . . . . . . . . . 359

14.7.5.3.2 Aromatization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

14.7.5.3.2.1 By Elimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

14.7.5.3.2.1.1 Method 1: Dehydration of 10H-Dibenzo[b,e]thiopyran-10-ols . . . . . . . . . . . 360

14.7.5.3.2.2 By Reduction and Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

14.7.5.3.2.2.1 Method 1: Reduction and Dehydration of 10H-Dibenzo[b,e]thiopyran-10-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

14.7.5.3.2.3 By Addition of Metal Reagents and Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

14.7.5.3.2.3.1 Method 1: Addition of Grignard Reagents to 10H-Dibenzo[b,e]thiopyran-10-ones and Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362

14.7.5.3.2.3.2 Method 2: Addition of Lithium Reagents to 10H-Dibenzo[b,e]thiopyran-10-ones and Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375



XXXIV Table of Contents

14.7.5.3.2.4 By O-Esterification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388

14.7.5.3.2.4.1 Method 1: O-Esterification of 10H-Dibenzo[b,e]thiopyran-10-ones . . . . . . 388

14.7.5.3.2.5 By Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389

14.7.5.3.2.5.1 Method 1: Oxidation of a Dispiro[thioxanthene-9,4¢-benzodithiophene-5¢,9¢¢-thioxanthene] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389

14.7.5.3.2.5.2 Method 2: Oxidation of 10-Methylene-10H-dibenzo[b,e]thiopyran-10-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391

14.7.5.3.2.5.3 Method 3: Oxidation of 14-Phenyldibenzo[a,j]thioxantheniumTetrafluoroborate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392

14.7.5.3.2.5.4 Method 4: Oxidation of Bis(1,9-dimethoxy-9H-thioxanthen-9-ylidene)methane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393

14.7.5.3.2.5.5 Method 5: Oxidation of 2-Methyl-1-(10H-dibenzo[b,e]thiopyran-10-ylidene)-2,3-dihydro-1H-benzo[f]benzothiopyran . . . . . . . . 394

14.7.5.3.2.5.6 Method 6: Oxidation of Bis(benzothia)-Fused Quinodimethanes . . . . . . . . 394

14.7.5.3.2.5.7 Method 7: Oxidation of Sulfur-Containing Quinodimethane-EmbeddedAcenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

14.7.5.3.2.5.8 Method 8: Oxidation of 1-Benzothiopyrano[2,3-b]thioxanthene . . . . . . . . 396

14.7.5.3.2.6 By Acidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

14.7.5.3.2.6.1 Method 1: Acidification of Ketals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397


14.7.5.3.3.1 Of Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

14.7.5.3.3.1.1 Method 1: Reaction with a Phosphite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

14.7.5.3.3.1.2 Method 2: Reaction with a Phosphoramidite . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

14.7.5.3.3.2 Substitution of Heteroatoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

14.7.5.3.3.2.1 Method 1: Reaction with Aniline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

14.7.5.3.3.2.2 Method 2: Treatment with Pyridine Hydrochloride . . . . . . . . . . . . . . . . . . . . . 400

14.7.5.3.3.3 Miscellaneous Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401

14.7.5.3.3.3.1 Method 1: Amidation of Carboxylic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401

14.7.5.3.3.3.2 Method 2: Esterification of Carboxylic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . 402

14.7.5.3.3.3.3 Method 3: Transformation of Thioamides to Amides . . . . . . . . . . . . . . . . . . . 402

14.7.5.3.3.3.4 Method 4: Hydrolysis of Phosphonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404

14.8 Product Class 8: Thiopyranones and Thiopyranthiones

14.8.6 2020Thiopyranones and ThiopyranthionesZ. Wang, T. Shi, and H.-H. Zhang

14.8.6 Thiopyranones and Thiopyranthiones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

14.8.6.1 2H-Thiopyran-2-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

14.8.6.1.1 Synthesis by Ring Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

14.8.6.1.1.1 Method 1: Reaction of Pyranones with Sodium Thiolate . . . . . . . . . . . . . . . . 407



http://orcid.org/0000-0003-4134-1779http://orcid.org/0000-0003-4118-8022

XXXVTable of Contents

14.8.6.2 2H-Thiopyran-2-thiones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408


14.8.6.2.1.1 Formation of One S-C Bond and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . 40814.8.6.2.1.1.1 Method 1: Reactions of 1-Aryl-5,5-dichloropenta-2,4-dienones with

Thiourea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408

14.8.6.2.1.1.2 Method 2: Reaction of 1,4-Dilithiobuta-1,3-dienes with Carbon Disulfide 409

14.8.6.2.1.1.3 Method 3: Reaction of 4-Phenyl-1,2-dithiole-3-thione withb-Arylacrylonitrile and b-Arylcrotonitrile Derivatives . . . . . . . . 411

14.8.6.2.1.1.3.1 Variation 1: Reaction of 4-Phenyl-1,2-dithiole-3-thione withArylidene(cyano)acetamide Derivatives . . . . . . . . . . . . . . . . . . . . . 412

14.8.6.2.1.1.3.2 Variation 2: Reaction of 4-Phenyl-1,2-dithiole-3-thione withN-Arylcyanoacetamide Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . 413

14.8.6.2.1.2 Formation of One S-C Bond and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . 41414.8.6.2.1.2.1 Method 1: One-Pot Reactions of Ketones, Malononitrile, and Carbon

Disulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414


14.8.6.2.2.1 Method 1: Rearrangement of a Trithiapentalene System under the Actionof Sodium Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415

14.8.6.3 4H-Thiopyran-4-ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416


14.8.6.3.1.1 Formation of One S-C Bond and One C-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . 41714.8.6.3.1.1.1 Method 1: Reactions of Aroylacetones with Carbon Disulfide . . . . . . . . . . . 417

14.8.6.3.1.1.2 Method 2: Diels–Alder Reaction between Danishefsky’s Diene and2,2,2-Trifluoro-1-morpholinoethanethione . . . . . . . . . . . . . . . . . . 417

14.8.6.3.1.1.3 Method 3: Rhodium-Catalyzed 1,1-Hydroacylation of Thioacylcarbeneswith Alkynyl Aldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418

14.8.6.3.1.2 Formation of Two S-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42014.8.6.3.1.2.1 Method 1: Addition of Sodium Sulfide or Its Equivalent to Dialkynyl

Ketones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420

14.8.6.3.1.2.1.1 Variation 1: Addition of Thiourea to Dialkynyl Ketones . . . . . . . . . . . . . . . . . . 422

14.8.6.3.1.2.2 Method 2: [5C + 1S] Annulation Reactions betweena-[(Dimethylamino)propenoyl]ketene S,S-Acetals andSodium Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422

14.8.6.3.1.3 Formation of One S-C Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42314.8.6.3.1.3.1 Method 1: Tandem Iodocyclization and Dehydroiodination of a-Alkenoyl

Ketene S,S-Acetals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423


14.8.6.3.2.1 Method 1: Transformation of Pyran-4-ones into Thiopyran-4-ones . . . . . . 426

14.8.6.3.3 Aromatization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427

14.8.6.3.3.1 Method 1: Dehydrogenation of Tetrahydrothiopyran-4-ones . . . . . . . . . . . 427

14.8.6.3.3.1.1 Variation 1: Dehydrogenation of a 2,3-Dihydro-4H-thiopyran-4-one . . . . . 427



XXXVI Table of Contents

14.8.6.4 4H-Thiopyran-4-thiones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428


14.8.6.4.1.1 Formation of One S-C Bond and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . 42814.8.6.4.1.1.1 Method 1: Reaction of a High Excess of the Monoanion of Ethyl

Thioglycolate with 1,2-Dichloro-1,2-diiminoethane . . . . . . . . . 428

14.8.6.4.1.2 Formation of Two S-C Bonds and Two C-C Bonds . . . . . . . . . . . . . . . . . . . . . . . . 43014.8.6.4.1.2.1 Method 1: Zinc(II) Chloride Catalyzed Reaction between 1,3-Dithiolane-

2-thione and Dibenzoylacetylene . . . . . . . . . . . . . . . . . . . . . . . . . . . 430


14.8.6.4.2.1 Method 1: Rearrangement of Trithiapentalene System under Action ofSodium Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430

14.8.6.4.2.2 Method 2: Unusual Heterocyclic Atom-Exchange Reaction withLawesson’s Reagent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430


14.8.6.4.3.1 Method 1: Transchalcogenization of 4H-Thiopyran-4-ones . . . . . . . . . . . . . . 432

14.10 Product Class 10: Selenopyrylium and Benzoselenopyrylium Salts

14.10.3 2020Selenopyrylium and Benzoselenopyrylium SaltsW. Wei and X. Zhao

14.10.3 Selenopyrylium and Benzoselenopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . 435

14.10.3.1 Selenopyrylium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

14.10.3.1.1 Synthesis by Aromatization via Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

14.10.3.1.1.1 Method 1: Use of Organolithium Reagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

14.10.3.1.1.2 Method 2: Use of Grignard Reagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437

14.10.3.1.2 Synthesis by Substituent Modification via Condensation Reaction . . . . . . . . . . 440

14.10.3.1.2.1 Of Carbon Functionalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440

14.10.3.1.2.1.1 Method 1: Condensation of 4-Methylselenopyrylium Salts withUnsaturated Phenyliminium Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . 440

14.10.3.1.2.1.2 Method 2: Condensation of 4-Methylselenopyrylium Salts with(4H-Selenopyran-4-ylidene)acetaldehydes . . . . . . . . . . . . . . . . . . 445

14.10.3.1.2.2 Of Oxygen Functionalities .

Documents

Science of Synthesis KnowledgeUpdates 2020/3...4.4.28.17.9 Synthesis of a-Silyl Amines from Silylmethyl Azides ..... 37 4.4.28.17.9.1 Method 1: a -Silyl Amines by Ruthenium-Catalyzed