Catalytic Asymmetric Acylation of Racemic Secondary Alcohols with Benzoyl Chloride in the Presence of a Chiral Diamine

Nonenzymatic kinetic resolution of racemic secondary alcohols is an efficient synthetic method to obtain optically active compounds in organic chemistry. Catalytic asymmetric acylation of racemic secondary alcohols has been successfully performed with achiral benzoyl chloride in the presence of only 0.3 mol% of chiral diamine (3) derived from (S)-proline, combined with 0.5 equivalent of triethylamine. This asymmetric acylation of various racemic cyclic secondary alcohols, 5, 6, or 8 membered cycloalkanols (1a–1c), hydroxyesters (1d and 1e), and bromohydrins (1f and 1g) gave the corresponding optically active benzoates (84–97% ee) and unreacted alcohols (79–95% ee). Racemic acyclic secondary alcohols (1h–1j) were also acylated in moderate enantioselectivity.