Intramolecular 1,4-Dipolar Cycloadditions of Cross-Conjugated Heteroaromatic Betaines. Synthesis of Hexahydrojulolidines and Related Peri- and Ortho-Fused Ring Systems

Article abstract of DOI:10.1021/jo00117a035

3-Alkenyl 2-lactams react with (chlorocarbonyl)phenylketene to give nonisolable anhydro-4-hydroxy-2-oxo-1,3-oxazinium hydroxides which undergo regio- and stereospecific 1,4-dipolar cycloaddition in moderate yields to produce cycloadducts containing a carb