A Flexible Route to Chiral 2-<i>endo</i>-Substituted 9-Oxabispidines and Their Application in the Enantioselective Oxidation of Secondary Alcohols

Abstract

A new and flexible route to enantiomerically pure bi- and tricyclic 9-oxabispidines has been developed with use of (1R,5S)-7-methyl-2-oxo-9-oxa-3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acid tert-butyl ester as the common late-stage intermediate. The 9-oxabispidines synthesized were evaluated as the chiral ligands in the Pd(II)-catalyzed oxidative kinetic resolution of secondary alcohols giving good to excellent selectivity factors of up to 19.