Fukuyama reduction

Fukuyama reduction
Named after	Tohru Fukuyama
Reaction type	Organic redox reaction
Identifiers
Organic Chemistry Portal	fukuyama-reduction
RSC ontology ID	RXNO:0000680

The Fukuyama reduction is an organic reaction and an organic reduction in which a thioester is reduced to an aldehyde by a silyl hydride in presence of a catalytic amount of palladium. This reaction was invented in 1990 by Tohru Fukuyama.[1] In the original scope of the reaction the silyl hydride was triethylsilane and the catalyst palladium on carbon:

Fukuyama reductions are used for the conversion of carboxylic acids (as thioester precursor) to aldehydes which is considered a difficult procedure because of the ease of secondary reduction to an alcohol.

Reaction mechanism

The basic reaction mechanism for this reaction takes place as a catalytic cycle:

Oxidative addition: ${{\text{R-C(O)-SR}}{}+{}\mathrm {Pd} {\vphantom {A}}^{0}{}\mathrel {\longrightarrow } {}\mathrm {RC} (\mathrm {O} ){-}\mathrm {Pd} {\vphantom {A}}^{\mathrm {II} }{-}\mathrm {SR} }$
Transmetallation: ${{\mathrm {RC(O){\text{-}}Pd^{II}-SR} }{}+{}\mathrm {R} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {SiH} {}\mathrel {\longrightarrow } {}{\mathrm {RC(O){\text{-}}Pd^{II}-H} }{}+{}\mathrm {R} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {Si} {-}\mathrm {SR} }$
Reductive elimination: ${\mathrm {RC} (\mathrm {O} ){-}\mathrm {Pd} {\vphantom {A}}^{\mathrm {II} }{-}\mathrm {H} {}\mathrel {\longrightarrow } {}{\text{RC(O)-H}}{}+{}\mathrm {Pd} {\vphantom {A}}^{0}}$

Scope

In a variation of the Fukuyama reduction the core BODIPY molecule has been synthesized from the SMe-substituted derivative:[2] Additional reagents are copper(I)-thiophene-2-carboxylate (CuTC), Pd(dba)2 and tri(2-furyl)phosphine

In the related Fukuyama coupling the hydride is replaced by a carbon nucleophile.

References

^ Facile reduction of ethyl thiol esters to aldehydes: application to a total synthesis of (+)-neothramycin A methyl ether Tohru Fukuyama, Shao Cheng Lin, Leping Li J. Am. Chem. Soc., 1990, 112 (19), pp 7050–7051 doi:10.1021/ja00175a043
^ The Smallest and One of the Brightest. Efficient Preparation and Optical Description of the Parent Borondipyrromethene System. I. J. Arroyo, R. Hu, G. Merino, B. Z. Tang, E. Peña-Cabrera, J. Org. Chem. 2009, ASAP

[1] Facile reduction of ethyl thiol esters to aldehydes: application to a total synthesis of (+)-neothramycin A methyl ether Tohru Fukuyama, Shao Cheng Lin, Leping Li J. Am. Chem. Soc., 1990, 112 (19), pp 7050–7051 doi:10.1021/ja00175a043

[2] The Smallest and One of the Brightest. Efficient Preparation and Optical Description of the Parent Borondipyrromethene System. I. J. Arroyo, R. Hu, G. Merino, B. Z. Tang, E. Peña-Cabrera, J. Org. Chem. 2009, ASAP