Rationalisation of cycloaddition behaviour by use of Hückel frontier molecular orbitals

Abstract

A simple method for predicting various aspects of cycloaddition reactions is tested with particular attention to reactivity and electroselectivity, but also including regioselectivity, periselectivity, and stereoselectivity (exo/endo in diene reactions). The method combines three techniques: (a) the Frontier Molecular Orbital approach, (b) potential energy diagrams, and (c) Hückel calculation (by computer). The computer method is easy to apply since it requires only standard parameters for atoms and bonds, and the whole technique is suitable for devising new syntheses of organic compounds.