Diels–Alder reactions of methyl-N-acyl-α,β-dehydroalaninates with cyclopentadiene

Abstract

A study has been made of the Diels–Alder reaction of methyl-N-acetyl (and benzoyl)-α,β-dehydroalaninates with cyclopentadiene. In the reaction of methyl-N-acetyl-α,β-dehydroalaninate total conversion is obtained under several conditions, while the N-benzoyl derivative shows a lower reactivity. The stereoselectivity of the reaction is determined by 1H nuclear magnetic resonance spectroscopy. Perturbation MO calculations, using wave functions generated by the MNDO method, are used to rationalize the relative reactivity of the dienophiles and the stereoselectivity observed.