Stereochemistry of Diels-Alder Reactions at High Pressure. II. Influence of High Pressure on Asymmetric Induction in Condensation of (−)-Di-(R)-menthyl Fumarate with Butadiene and Isoprene

Abstract

Abstract The high-pressure Diels-Alder condensation of (−)-di-(R)-menthyl fumarate with butadiene and isoprene, followed by reduction of the adducts with lithium aluminium hydride, produced (1S,2S)-(+)-4-cyclohexene-1,2-dimethanol and (1S,2S)-(+)-4-methyl-4-cyclohexene-1,2-dimethanol in 6.2–12.8% optical yield, depending on the pressure applied. Results of asymmetric synthesis were discussed in light of the concept of parallel transition states. An interpretation of the thermal and Lewis-acid-catalyzed asymmetric Diels-Alder condensations using (−)-di-(R)-menthyl fumarate was proposed.