Nitrones and oxaziridines. XXI electronic substituent effects in nitrone cycloadditions to highly Polarized Alkenes

Abstract

1, 3-Dipolar cycloaddition reactions of nitrones-particularly N-(2'-pyridylmethylene)aniline N-oxide -with arylmethylene cyanoacetates exclusively yield 4, 4-disubstituted isoxazolidines, identifiable by 1H n.m.r. spectroscopy and isolable in some cases. Comparative kinetic experiments provide evidence for at least non-synchronous addition via a dipolar intermediate or possibly even two-step addition via a discrete zwitterionic intermediate. © 1978 Australian Journal of Chemistry.