Tobe LaboratoryM1 Yamane Hiroshi

Synthesis of novel polycyclic aromatic hydrocarbons by transannular cyclization of

dehydrobenzoannulenes

Polycyclic Aromatic Hydrocarbons (PAH)PAH ・・・多環状芳香族化合物

picene

9,9’-bifluorenylidene

Superconducting materials

K - Doped

20K Electron Acceptors ofLightweight Organic devices

Kubozono, Y. et al. Nature, 2010, 464, 76-79. Wudl, F. et al. Angew. Chem. Int. Ed. 2009, 49, 532-536.

~Introduction~

Reactivity of alkyne

πbond σbond

πbond

Bond energy : σbond > πbond(1) >πbond(2) (kJ/mol) 369 268 202

Alkyne has high reactivity

~Introduction~

Tandem Cyclization Reaction by Electrophile

Scheme 1. Tandem cyclization reaction by electrophilic

Br+

Br Br

Br

Br -

Br

Br

Br

Br

Br

b

a

b

a

Lutz, V. et al. Angew. Chem. Int. Ed. 2003, 42, 5757−5760.

Tandem Cyclization ・・・連続環化

4

Low selectivity and low yield

~Introduction~

Motivation

・ Low selectivity・ Low yield

Noncyclic compounds Distance between acetylenes is loose

Cyclic compounds Distance between acetylenes is fixed

・ Improvement of selectivity・ Improvement of yield・ Induction of spontaneous reaction

~Purpose of my reserch~

Transannular cyclization for cyclic compounds

OC4H9

OC4H9

C4H9O

C4H9O

1. n-BuLi2. BuI

THF

Bu

BuC4H9O

C4H9O

OC4H9

OC4H9

44%

Br

Br

Br

Br

Br2

CHCl30 °C r.t.

BuBu

1. n-BuLi, THF, -78 °C2. H2O

59%

32%

Scheme 2. Transannular cyclization of cyclic compounds by several ways

~Purpose of my reserch~

3.15 Å 3.17 Å

Three-dimentional model of 1

1

Figure 1. Cariculated three-dimentional model of 1 (calculations are based on B3LYP/6-31G*)

Prediction of reaction of 1 with nucleophile

Bu

Bu Bu Bu

Bu

H+

H1 2

Scheme 3. Predicted cyclization reaction of 1

Synthesis route of 1

n-BuLi, t-BuOK

hexane

Li

Li

B(OiPr)3B(OH)2

(HO)2B

OHC

CHO

HH

Pd(PPh3)2Cl2, CuI, I2

THF, (i-Pr)2NH

1

3 4 5 6

8

ether

CHOBr

PPh3, CBr4, Zn

CH2Cl2

LDA

THF

Pd(PPh3)4, K2CO3

Br

Br

Br

Br

toluene, H2O, ethanol

7

9Sceme 4. Synthesis route of 1

Prediction of reaction of 7

9

HH

Pd(PPh3)2Cl2, CuI, I2

THF, (i-Pr)2NH

7

2H+

1 benzyne intermediate

Scheme 5. Reaction of 7 passed through benzyne intermediate

Computational results for [2+4] diyne-yne cycloaddition

＋

0.0 kcal/mol

-51.4

E

TS1+36.5

High potential Energy

reactive coordinate

Aida A. et al. J. Org. Chem. 2011, 76, 9320-9328.

Property of benzyne

benzene benzyne

O

O

O

Overlap of each p orbital is little

sp2 orbitals are conjugated

Electrons are localized

Scheme 6. Diels-Alder reaction of benzyne and furan

More destabilization

stabilization

Future work

9

HH

Pd(PPh3)2Cl2, CuI, I2

THF, (i-Pr)2NH

7

2H+

O

O

Scheme 8. Trapping of benzyne intermediate by furan

Conclusion

• Acetylene-integrated 1 is designed.

• After the synthesis of 1, 7 is considered generated via benzyne intermediates.

• I will confirm the presence of a benzyne intermediate by furan.