Iridium Catalyst System for Transfer Hydrogenation

Wu Hua

2012-6-9

Shun-Ichi Murahashi. J. Am. Chem. Soc. 1998, 120, 4244-4245

Iridium Hydride Complex Catalyzed Addition of Nitriles to Carbon-Nitrogen Triple Bonds of Nitriles

R1 C

H

H

CN IrLnR1 C

H

IrLnH

CN

NC-R2

R1 C

H

IrLnH

CNNC-R2

Ln = PR3, CO, H

R1 C

H

C

CN

NIrLnH

R2-IrLn

R1 C

H

C

CN

NH

R2 C CNH2

R2

R1

CN

R1CH2CN + C NR2 Ir cat.

NH2

R2NC

R1

A mixture of nucleophile (1.0 mmol), nitrile (2.0 mmol), and IrH(CO)(PPh3)3 (3 mol %) in dry THF (0.25 mL) was stirred at 120 °C for 12 h under argon.

Mechanism:

Yasutaka Ishii. Angew. Chem. Int. Ed. 2001, 40, 2534-2536

A Three-Component Coupling Reaction of Aldehydes, Amines, and Alkynes

H

R2

NR1

IrILn NR1R1

NR1R1

IrILnH

NR1R1

IrIIILnHR2

NR1R1

IrIIILnH

IrIIILn

R2

NR1 H

R2

n-Pr

O

H+ n-Pr NH2 + n-Hex

cat.[{Ir(cod)Cl}2]

THF, 60 oC

n-Hex

N n-Prn-Pr

Ken-ichi Fujita, Ryohei Yamaguchi. Tetrahedron Letters. 2003, 44, 2687–2690

N-Alkylation of amines with alcohols catalyzed by a Cp*Ir complex

NH2

NH2

NH2

NH2

MeO

Cl

OH

OH

OH

OH

Yield

85

92

93

95

R1

NH2

+R2 R3

OH[Cp*IrCl2]25.0 mol%K2CO35.0 mol%

Toulene110 oC, 17 h

R1

N

R2

R3H

Substrates:

Mechanism:

[Cp*IrCl2]2

R2

OH

R3+ K2CO3

O

R2

R3

[Cp*Ir]

R2

O

R3

R1NH2

H2O

[Ir*Cp] H

N

R2

R3R1N

R2

R3

R1

[Cp*Ir]

R2

OH

R3

R2

NHR1

R3

The base (K2CO3) wouldstimulate the first oxidation step

Kazuhiko Taguchi, Yasutaka Ishii. J. Am. Chem. Soc. 2004, 126, 72-73

An Efficient Direct r-Alkylation of Ketones with Primary Alcohols Catalyzed by [Ir(cod)Cl]

2/PPh3/KOH System without Solvent

Kazuhiko Taguchi, Yasutaka Ishii. J. Am. Chem. Soc. 2004, 126, 72-73

i) R1CH2OH[Ir(cod)Cl]2 R1CHO + LnIr

H

H

ii) R1CHO + R2

O base

R1 R2

O+ H2O

iii) R1 R2

O LnIrH

H

R1 R2

O

Kazuhiko Taguchi, Yasutaka Ishii. J. Am. Chem. Soc. 2004, 126, 72-73

Mechanism:

Tomoya Mizuta, Satoshi Sakaguchi, and Yasutaka Ishii. J. Org. Chem. 2005, 70, 2195-2199

Catalytic Reductive Alkylation of Secondary Amine with Aldehyde and Silane by an Iridium Compound

Tomoya Mizuta, Satoshi Sakaguchi, and Yasutaka Ishii. J. Org. Chem. 2005, 70, 2195-2199

IrLn

Et3SiD

Et3Si-Ir-DLn

Et3SiOH

H2O

H-Ir-D

Ln

N

R'

R R

H

R'

Ir

NR R

D Ln

D

R'

Ir

NR R

H Ln

H

R'

D

NR R

D

R'

D

NR R

+

+

Plausible Mechanism:

Guerbet Reaction of Primary Alcohols

Yasutaka Ishii. J. Org. Chem. 2006, 71, 8306-8308

10 mol% 1,7-octadiene

ROH2

1 mol% [Cp*IrCl2]2

40 mol% t-BuOK

p-xylene 0.5 mL

R

OHR

ROH

dehydrogenation

- 2H22 R

O

H

+ ROH

H

RO

OHR

HB:

-H2OR

OR hydrogenation

+ 2H2 ROH

R

Guerbet alcohols

Mechanism of Guerbet reaction:

Yasutaka Ishii. Org. Lett. 2006, 8, 2459-2462

New Coupling Reaction of Secondary Amines, Aldehydes, and Alkynes Catalyzed by an Iridium Complex

R1 NH

R1 +R2 H

O+ R3

[IrCl(cod)]2

1,4-dioxane50oC, 3h

R3 = R4CH2

R1 N R1 R1 N R1

+R2

R4 R4

R2

Mechanism:

R1 N R1

IrH2

R1 NH

R1

R1 N R1

R3

R2

R1 N R1

R2

R4 (R3 = R4CH2)

R1 NH

R1 + R3

Ir

R1 N R1

R3

R1 N R1

R3

Ir-H

R2

O

HR1 N R1

R3

R2

OIr

Ir

- H2O

The reaction is initiated!

Yasutaka Ishii. Tetrahedron Lett. 2006, 47, 9199–9201

Oxidative dimerization of primary alcohols to esters catalyzed by iridium complexes

R OH

[IrCl(coe)2]2 (3mol%)

95oC, 15h

open air

R O R

O

R OH

R H

O

R OH

R O

OH

R

R O

O

R

LnIr

LnIrH2

LnIr

1/2 O2

H2O

Yasutaka Ishii. Chem. Commun. 2007, 2850–2852

Alkylation of active methylene compounds with alcohols catalyzed by an iridium complex

NC

O

On-Bu+ OH

CN

O

On-Bu5 mol% [IrCl(cod)]2, 20 mol% PPh3

p-xylene, 130oC, 15h

R2 OH LnIr LnIrH2R2 O+ +

O

NCR1

+ R2 OLnIrH2

R2

CN

O

R1 + LnIr + H2O

a)

b)

Mechanism:

Yasutaka Ishii. Bull. Chem. Soc. Jpn. 2008, 81, 689–696

Synthesis of Diketones and ω -Hydroxy Ketones from Methyl Ketones and , α,ω –Diols by an [IrCl(cod)]2/PPh3/KOH System

R

O+

HO OHn

5 mol% [IrCl(cod)]2

PPh310 mol%

10 mol% KOH

without solvent100oC, 15h

R

O O

Rn

Iridium-Catalyzed α-Alkylation of Acetates with Primary Alcohols and Diols

O

OBu-t + ROH

[IrCl(cod)]2/PPh3

tert-BuOK, tert-BuOH

100oC, 15h

O

OBu-tR

Yasutaka Ishii. J. Am. Chem. Soc. 2010, 132, 2536–2537

Yasutaka Ishii. J. Org. Chem. 2009, 74, 628–633

N-Heterocyclization of Naphthylamines with 1,2- and 1,3-Diols Catalyzed by an Iridium Chloride/BINAP System

NH2

+ HO OH

IrCl3.3H2O (5mol%)

BINAP (7.5mol%)Na2CO3 (8mol%)

Mesitylene (3 mL)reflux (169oC)

under Air, 15h

N

Yasutaka Ishii. J. Org. Chem. 2009, 74, 628–633

HN N

IrLn

NH

NH IrLn

NH

LnIr LnIrHN

H2O O2

HO OH

LnIr [LnIrH]

HO H

O

NH2

HNLnIr[LnIrH]

H2O

OH

N OH

LnIr [LnIrH] HN H

ONH2

H2O

HN N

R OH + Ar Me

[Ir(OH)(cod)]2

P(n-Otc)3

Toluene100oC 15h,

R

OH

Ar

Yasutaka Ishii. Org. Lett., 2009, 11, 3510-3513

Iridium-Catalyzed Coupling Reaction of Primary Alcohols with 1-Aryl-1-propynesLeading to Secondary Homoallylic Alcohols

Yasutaka Ishii. Org. Lett., 2009, 11, 3510-3513

Iridium-Catalyzed Coupling Reaction of Primary Alcohols with 1-Aryl-1-propynesLeading to Secondary Homoallylic Alcohols

Yasutaka Ishii. Chem. Eur. J. 2010, 16, 1883 – 1888

"LnIr" "LnIrH2"

R

OH

Ar

R

O

Ar

IrHLn

R

O

H

Ir O

R

H

H

ArH

Ln

HH

Ar H

H

Ir

H

Ln

Ir CH3

HAr

HLn

A Plausible Reaction Mechanism:

Yasutaka Ishii. Angew. Chem. Int. Ed. 2011, 50, 8618 –8622

Iridium-Catalyzed Reactions of w-Arylalkanols to α,ω –Diarylalkanes Diarylalkanes

OH

R

route A [(Cp*IrCl2)2]

p-xylene

120oC, 4h

n=1

R

n n n

[(Cp*IrCl2)2]

t-BuOK1,4-dioxane120oC, 24h

n=2-5

(Step 1)

route B

R

n-1

HO

n-1R

[(Cp*IrCl2)2]

[{IrCl(cod)}2]/dppe

k2CO3

Mesitylene

160oC, 24h

(Step 2)

R

Yasutaka Ishii. Angew. Chem. Int. Ed. 2011, 50, 8618 –8622

O

H

O Hbase H2O

OH

OH

2LnIrH2

2LnIr

O HLnIrH2

LnIr

2

2

LnIr

oxidative addition

decarbonylation

H-elimination

Step 1

Step 2

Summary

a. Reaction Temperature

b. Rh, Ru, Ni

c. Development of hydrogen transfer reactions