On the Stability of Disubstituted Cyclobutenes - A Computational Study.

A computational study of the electrocyclic ring-opening of 2-substituted cyclobutenecarboxylic acids is presented. Detailed calculations suggest a model to predict whether the product of nucleophilic alkylation of a bicyclic lactone electrophile will be a cyclobutenecarboxylic acid or its dienoic acid isomer, based on the used nucleophile.