Convergent synthesis of azabicycloalkenones using squaric acid as platform

The synthesis of azabicycloalkenones bearing a vinylogous amide moiety was achieved by means of the rhodium-catalyzed decarbonylative cycloaddition of cyclobutenediones with a pendant alkene. The starting cyclobutenediones were efficiently prepared from appropriate squaric acid monoesters and N-benzylalkenylamines under microwave heating conditions.