Stereoselective azepine-ring formation through ene reactions of 3-(alk-2-enyl)amino-2-cyanoacrolein derivatives

The reaction of 3-[N-(alk-2-enyl)benzylamino]-2-cyanoacroleins 9 with prima ry amines 12 and 13 gave 4,5-dihydro-1-Hazepines 14 and 15 stereoselectivel y, through an intramolecular ene reaction of the imine derivatives of 9. Si milarly, carbonyl-ene reaction of acrolein derivatives 9, and olefin-ene re action of their conjugated diene compounds 22, and 24-27 are also discussed . These ene reactions established an efficient synthetic approach toward mo nocyclic azepine ring formation.