Asymmetric [3+2] cycloaddition reaction of a chiral cyclic nitrone for the synthesis of new tropane alkaloids

Abstract

The 1,3-dipolar cycloaddition of a chiral nitrone with α,β-unsaturated lactones was carried out to give the corresponding isoxazolidines. Tetrahydro-1,3-oxazines with an oxa-tropane skeleton were obtained in one step by alkylation. The structures of several of these compounds were corroborated by X-ray diffraction and molecular modelling studies confirmed the results and proposed a mechanism for their formation.