Preparation of Enantiopure Norbornane Ligands Bearing Both (2S,3S)-Bis(phosphinomethyl) and 7-syn-Oxygen Functional Groups and an Application to Rhodium-Catalyzed Asymmetric Hydrogenation

Abstract

Enantiopure bicyclo[2.2.1]heptane derivatives having both (2S,3S)-bis[(diphenylphosphino)methyl] and 7-syn-oxygen functional groups were synthesized by using diastereoselective Diels-Alder reaction of di-(1R)-menthyl fumarate and 5-trimethylsilylcyclopentadiene followed by silver-promoted stereospecific frame rearrangement of a bromolactone intermediate. Rhodium-catalyzed asymmetric hydrogenations were carried out using the diphosphines as a chiral ligand.