Stereoselective Tandem Reductive Aldol Reaction

Significance

The article presents a new copper(I)-catalyzed asymmetric system for the tandem reductive aldol reaction of methyl acrylate with different aldehydes. In this reaction, the nucleophile is generated in situ by the conjugated addition of PhSiH₃ to the β-position of the acrylate. The use of a more economic copper(I)-catalyst {[CuF(PPh₃)₃ ^.2MeOH]} instead of the more expensive rhodium or iridium variants, together with TaniaPhos as chiral ligand promotes a stereoselective addition to various aldehydes. The respective β-hydroxy esters can be obtained with high chemoselectivities. The diastereoselectivities of this reaction, however, are rather moderate, slightly favoring the syn product. Nevertheless, good to excellent enantioselectivties are observed for a wide range of cyclic aliphatic, aromatic and hetero­aromatic aldehydes as substrates.