Crystallographic Evidence for Cyclopropane Ring Formation in Isotwistenes Obtained by Thermal Cascade Reactions of Cyclopentadienone with Acyclic Conjugated Dienes

Abstract

The molecular structure of the double Diels–Alder (DDA) adduct derived from three-step thermal cascade reactions of 2,5-bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone with ethyl sorbate is elucidated by single crystal X-ray analysis. The structural features and the reaction mechanism of the adduct are discussed on the basis of density functional theory (DFT) calculation results.