Chemoenzymatic synthesis of (S)- and (R)-mappicines and their analogues †

Abstract

The natural alkaloids, camptothecin and mappicine ketone were converted into racemic mappicine which on treatment with vinyl acetate in presence of the lipase Candida cylindracea(CCL) afforded (S)-mappicine acetate and (R)-mappicine. The acetate was chemically hydrolysed to (S)-mappicine. 9-Methoxycamtpothecin and 9-methoxymappicine ketone were similarly converted into (S)- and (R)-9-methoxymappicines.