Highly enantioenriched (R)-4-bromo-1-cyanobutyl acetate and (R)-5-bromo-1-cyanopentyl acetate were prepared by acetylcyanation of 4-bromobutanal and 5-bromopentanal, respectively, catalyzed by (S, S)-[(4, 6-bis (t-butyl) salen) Ti (μ-O)] 2 and triethylamine followed by enzymatic hydrolysis of the minor enantiomer. A cyclic procedure employing the same two chiral catalysts provided inferior results due to a slowly reached steady state ...
