Highly efficient chiral resolution and determination of absolute configuration of 2-alkanols by using a cyclopenta[b]furan derivative

The reaction of 3a-benzhydryl-3,3a,4,5-tetrahydro-2H-cyclopenta[b]furan and various 2-alkanols in the presence of a catalytic amount of pyridinium 4-tolunesulfonate in dichloromethane gave 3a-benzhydryl-6a-(1-methyl-aloxy)-hexahydrocyclopenta[b]furan in more than 90% chemical yields. The resulting diastereomeric mixture is easily separable on silica gel chromatography because of the large ΔRf value (briefly 0.1). Absolute configuration of the 2-alkanols can be easily estimated by the chemical shifts of 1H and 13C NMR of methyne group of the benzhydryl moiety.