Competitive Intramolecular Diels–Alder Reactions of bis-α,β-Unsaturated Ester Derivatives of Enzymatically Derived and Enantiopure cis-1,2-Dihydrocatechols. Enantiodivergent Synthesis of Monochiral Bicyclo[2.2.2]oct-2-enes

Abstract

bis-Crotonate and related α,β-unsaturated ester derivatives of readily available and enantiomerically pure cis-1,2-dihydrocatechols engage, upon heating in refluxing toluene, in two competitive intramolecular Diels–Alder reactions to give varying mixtures of chromatographically separable and pseudo-enantiomeric bicyclo[2.2.2]oct-2-enes. Such adducts, many of which have been characterized by single-crystal X-ray analysis, are likely to serve as useful building blocks in natural products synthesis.