2β, 3α-Dihydroxyurs-12-en-28-oic acid (6) is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi- synthesis of 6 was developed. Using the commercially available ursolic acid (1) as the starting materials, 6 was synthesized through five facile reactions with a high stereoselectivity and an overall yield of 47.3%. The structure of 6 was confirmed by optical ...
