8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

1/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

2/14

Properties of Ruthenium

Ruthenium has the widest range of oxidation states of any element

Ruthenium complexes can adopt several coordination geometries

Range of reactivity due to properties of Ru complexes:1. High electron transfer ability2. High Lewis acidity3. Low redox potentials4. Stabilities of reactive metallic species such as oxometals, metallacycles, and metal carbene complexes

Ru(0)

Ru(II)

Ru(III)

Ru(VI)

Ru(VII)

Ru(VIII)

5

5

6

6

4

4

4

trig. bipy.

trig. bipy.

octahedral

octahedral

tetrahedral

tetrahedral

tetrahedral

[Ru(NH 3)5Cl]2+

Ru(CO) 5

RuHCl(PPh 3)3

RuCl 2CO(PR 3)3

RuO 42-

RuO 4-

RuO 4

OxidationState

Coordinationnumber Geometry Example

Ru(CO) 42- Ru(CO) 5 RuO 4-2 0 +8

Regioselective Reductions

cat. RuHCl(PPh 3)31 atm H 2, 25 Cbenzene-ethanol

O

O

O

O

cat. RuCl 2(PPh 3)3100 atm H 2, 50 C

benzene(94%)

O

H OHcat. RuCl 3 /P(m-C 6H4SO 3Na) 3

20 atm H 2, 35 Ctoluene, buffer

97% conversion 99% selectivity

O

OH

O OO

cat. RuCl 2(PPh 3)312 atm H 2, 180 C

(99%)

O

O

O

O

O

O

O

cat. RuCl 2(PPh 3)324 atm H 2, 100 C

(72%) 9:1

LAH(70%)

1:19

J. Chem. Soc. Chem. Comm. 1976, 314.

Organometallics 1991, 10 , 2126. J. Organomet. Chem. 1982, 231 , 79.

J. Chem. Soc. Chem. Comm. 1967, 305.

Bull. Chem. Soc. Jpn. 1975, 48 , 2852.

2

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

3/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

4/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

5/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

6/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

7/14

Application in Total Synthesis: The Proposed Structure of Amphidinolide A

O

O

O

O

O

O

OO

OH

O

O

O

OO

O

OO

HO

HO

HO

O

OO

OH

Proposed structure of amphidinolide A; 58% yield for cycloisomerization

1. 10% CpRu(CH 3CN)3PF 62. H +

1. 10% Cp*Ru(CH 3CN)3PF 6

2. Piperidine

OFmoc

O

Cycloisomerization: 76% yield brsm as 3.5:1 mixture of branched and unbranched isomers

Trost JACS 2002, 124, 12420.

Ru catalyst

Ruthenacyclopentene: Intramolecular [5+2] Cycloaddition

Ru

Trost JACS 2000, 122 , 2379.

R

R

R

RuCpR

RuCp

R

RuCpR

R

Ru catalyst: 10 mol % CpRu(CH 3CN)3PF 6Solvent: DMF or acetoneMild conditions: conducted at rtBi- and Tricyclic cycloheptadienes formed ingood yields (73-92%)

7

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

8/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

9/14

Ru catalyst

Ruthenacyclopentadiene: [2+2+2] cycloaddition

Ru

Itoh JOC 1998, 63, 9610; Chem. Commun. 2000, 549.

R

R1

Ru

Ru

R

R1R

R1

Ru

R1

R

R

R1

R

R1

Steric interaction between R-group and metal center forces the larger group to be situated in the R 1-position.

Ruthenacyclopentadiene: [2+2+2] cycloaddition

MeO 2C

MeO 2C

1% Cp*Ru(COD)Cl

OItoh JOC 1998, 63 , 9610.

, 40 C

MeO 2C

MeO 2CO

(87%)

MeO 2C

MeO 2C

1% Cp*Ru(COD)Cl

(85%)DCE, rt

93:7, A:B

MeO 2C

MeO 2C

MeO 2C

MeO 2C

A

B

Itoh Chem. Commun. 2000, 549.

9

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

10/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

11/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

12/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

13/14

8/7/2019 Ruthenium in Organic Synthesis 2004_Cruz

14/14

Conclusion

Wide scope of reactions catalyzed or mediated by Ruthenium complexes

Relatively new area in C-C bond formation;50% literature cited in Trost's review was published in 1997 or later

"Prospects are clearly bright for more reactions to be discovered." --Trost

14