Producing optically active alpha-hydroxy-ketone(s), useful in synthesis

摘要

Preparation of optically active alpha-hydroxyketone derivatives of formula R-CHOH-CO-R (I) are prepared catalytically by benzoin condensation of aldehydes of formula RCHO (II) in the presence of a chiral triazolium carbene of formula (III). R = 1-30C aliphatic, cycloaliphatic, arylaliphatic, or aromatic; R1 = 1-30C alkyl or aryl (both optionally bonded by O, S or N), H, halo, CN, NO2 or 1-20C perhaloalkyl; R2, R3 = 1-30C alkyl or aryl; or R1+R3 complete a ring. R2 and/or R3 are chiral. (III) is preferably formed in situ, from a salt of formula (IV) or by elimination of HY from the triazoline of formula (V). X<-> = anion;Y = group that can be lost as HY. (III), (IV) and (V) are new.