Cycloaddition vs. Michael Addition in the Metal Halide/Amine-Induced Reactions of α-(Alkylideneamino) Esters with Electron-Deficient Olefins

Abstract
The lithiated intermediate derived from methyl 2-(benzylideneamino)propanoate and lithium bromide/triethylamine undergoes cycloaddition and Michael addition with methyl acrylate. 1,3-Dipole character of the intermediate is suggested on the basis of the product ratios obtained under a variety of conditions. The reaction mechanism via a four-centered transition state is proposed.