Fukuyama Reduction

The Fukuyama reduction involves the relatively mild oxidation of a thioester to the corresponding aldehyde, shown in Figure 1.^[1] It is a useful method to reduce carboxylic acids via a thioester, and demonstrates excellent functional group tolerance compared to other reduction methods.

Figure 1. The Fukuyama Reduction.

This reaction proceeds through a fairly typical palladium-based catalytic cycle, shown in Figure 2. Oxidative addition of the C(sp₂)-S bond to Pd(0) leads to an acylpalladium species. This then undergoes transmetallation with a silyl hydride acting as a hydrogen source. Et₃SiH was used in the seminal publication.^[1] Reductive elimination of this acylpalladium hydride affords the desired aldehyde.

Figure 2. Catalytic cycle of the Fukuyama reduction.

1. Fukuyama, S. C. L.; Leping, L. J. Am. Chem. Soc. 1990, 112, 7050 – 7051.