ORGN 297

(+)–Crobarbatic acid is a retrosynthon of crobarbatine, a biologically active compound found in the rare plant Crotalaria barbata R. The key synthetic challenge in preparing (+)-crobarbatic acid is generating the correct stereochemistry at the lactone ring's 5 position relative to the 4 position's chirality. This is complicated by the carbon atom at the 5 position being tetra-substituted. We are developing a solution to this synthetic challenge by an anodic oxidative cyclization. The anodic oxidation has been optimized and found to produce a single isomer in which the methyl groups are cis to each other. While this stereochemistry is applicable for other natural products, (+)–crobarbatic acid has a trans methyl relationship. Efforts to also produce this trans methyl stereochemistry are being made. This talk will cover the development of the anodic oxidative cyclization that leads to furanones and the synthetic schemes to obtain either desired chirality at the tetra-substituted carbon atom.