Enantioselective addition of thiophenylboronic acids to aldehydes using ZnEt2/Schiff-base catalytic system

Using Schiff-base amino alcohols as catalysts which were readily derived from natural amino acids in three steps, a series of valuable optically active thiophenyl methanols (4a–4n) were first obtained in good yields and high enantioselectivities (up to 96% ee) through the asymmetric addition of thiophenylboronic acid to aldehydes in the presence of ZnEt2 in toluene.