Catalyst-free reaction of 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates: synthesis of 1,2-dihydroquinolines and 2,3-dihydropyrroles.

Catalyst-free annulations of 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates have been successfully achieved under mild conditions. Specifically, the reaction of 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates with sulfur ylides furnished various 1,2-dihydroquinolines in generally high yields. Furthermore, [3+2]-annulations of 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates with α,β-unsaturated imines afforded a broad scope of polysubstituted 2,3-dihydropyrroles with high efficiency.