Regioselective Diversification of a Cardiac Glycoside, Lanatoside C, by Organocatalysis

摘要

Acylation of lanatoside C in the presence ofnorganocatalyst 5 gave the C(4′′′′)-O-acylate in up to 90%nregioselectivity (catalyst-controlled regioselectivity). Variousnfunctionalized acyl groups can be introduced at the C(4′′′′)-nOH by a mixed anhydride method in the presence of 5 or thenrelated organocatalyst. On the other hand, DMAP-catalyzednacylation of lanatoside C gave the C(3′′′′)-O-acylate in up ton97% regioselectivity (substrate-controlled regioselectivity).nThus, diverse regioselective introduction of acyl groups amongneight free hydroxy groups of lanatoside C was achieved.