Unusual synthesis of dihydropyrido[2,1-a]isoindolone derivatives by radical cyclization of enamides of Baylis–Hillman adducts

During the radical cyclization of enamide derivatives 4 we found unusual formation of dihydropyrido[2,1-a]isoindolone derivatives 5. The enamides were synthesized in four steps from the Baylis–Hillman adducts of ortho-bromobenzaldehydes.