Total Synthesis of the α-Glucosidase Inhibitors Schulzeine A, B, and C and a Structural Revision of Schulzeine A

The enantioselective total synthesis of the potent a-glucosidase inhibitors schulzeine A, B, and C and a revision of the proposed C20' configuration of schulzeine A are reported. The central feature of our convergent route to this family of novel marine natural products is the preparation of the common benzo[a]quinolizidine subunit through a substrate-controlled, diastereoselective Pictet-Spengler cyclocondensation.