Short and efficient total synthesis of fraxinellone limonoids using the stereoselective Oshima-Utimoto reaction.

[reaction: see text] The catalytic diastereoselective Oshima-Utimoto reaction was employed for the construction of fraxinellone and related members of this limonoid family of natural products. After formation of the five-membered lactone, a stereoselective aldol reaction and olefin metathesis established the bicyclic ring system in the natural products.