A theoretical study on intramolecular anion radical [2Â +Â 2] cyclobutanation of bis(enones): Dramatic effects of the electron-deficient enone partners on the yielding of cyclobutane ring systems

► We report the first case of cycloaddition of aliphatic substituented bis(enones). ► We also provide significant new physical insight into the mechanism. ► The reaction proceeds via a 5-membered distonic anion radical intermediate. ► The first reaction step prefers a negative RC and the second needs a neutral one.