Synthesis of (R,R)- and (S,S)-Norphos

Abstract

Oxidation of (E)-1,2-bis(diphenylphosphanyl)ethene with hydrogen peroxide gave (E)-1,2-bis(diphenylphosphoryl)ethene. Diels-Alder reaction of (E)-1,2-bis(diphenylphosphoryl)ethene with cyclopentadiene yielded 2,3-bis(diphenyl-phosphoryl)bicyclo[2.2.1]hept-5-ene (NorphosO). rac-NorphosO was resolved with O,O-dibenzoyltartaric acid. (R,R)- and (S,S)-NorphosO were reduced with trichlorosilane to give 2,3-bis(diphenylphosphanyl)bicyclo[2.2.1 ]hept-5-ene [(R,R)- and (S,S)-Norphos].