Phosphine-catalyzed [4 + 3] annulation for the synthesis of highly functionalized bicyclo[3.2.2]nonadienes.

A phosphine-catalyzed [4 + 3] annulation of modified allylic carbonates with methyl coumalate was developed. This strategy offered a powerful method for the construction of bicyclo[3.2.2]nonadiene skeleton with high stereoselectivity.