Design and Synthesis of Oleanolic Acid Rings A and C Lactone Derivatives

Oleanolic acid (OA), a naturally occurring triterpene, was found to have a variety of biological and pharmacological properties. To expand its structural diversity, a series of oleanolic acid derivatives, including ring A and/or ring C expansion, were performed via Baeyer-Villiger reaction using m-CPBA and urea-hydrogen peroxide. The structures of all products were characterized by H-1 NMR, C-13 NMR and HRMS.