Asymmetric Aldol Reaction of Acetaldehyde and Isatin Derivatives for the Total Syntheses of ent-Convolutamydine E and CPC-1 and a Half Fragment of Madindoline A and B

The asymmetric aldol reaction of isatin derivatives and acetaldehyde has been developed using 4-hydroxydiarylprolinol as a catalyst, affording the aldol products with high enantioselectivity, these products being key intermediates in the synthesis of 3-hydroxyindole alkaloids. Short syntheses of ent-convolutamydine E and CPC-1 and a half fragment of madindoline A and B have been accomplished.