-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ-sulfanyl)acetic acid esters with aldehydes.

Aldol reactions belong to the most frequently used C-C bond forming transformations utilized particularly for the construction of complex structures. The selectivity of these reactions depends on the geometry of the intermediate enolates. Here, we have reacted octyl pentafluoro-λ-sulfanylacetate with substituted benzaldehydes and acetaldehyde under the conditions of the silicon-mediated Mukaiyama aldol reaction. The transformations proceeded with high diastereoselectivity. In case of benzaldehydes with electron-withdrawing substituents in the -position, -α-SF-β-hydroxyalkanoic acid esters were produced. The reaction was also successful with -substituted benzaldehydes and -fluorobenzaldehyde. In contrast, -methyl-, -methoxy-, and -ethoxybenzaldehydes led selectively to aldol condensation products with ()-configured double bonds in 30-40% yields. In preliminary experiments with an SF-substituted acetic acid morpholide and -nitrobenzaldehyde, a low amount of an aldol product was formed under similar conditions.