Kinetic resolution of γ-iodo allylic alcohols by the Sharpless asymmetric epoxidation reaction proceeds with very large rate differences for the two enantiomers, thus providing a highly efficient method for preparation of optically pure . The alcohols thus prepared can be readily converted into various secondary allylic alcohols through the coupling reaction with nucleophiles.
Novel 7-thiaprostaglandin E1 derivatives and congeners were synthesized by a stepwise three-component coupling process, which involves the introduction of α-side chains (thiols) and β-side chains (organocopper reagents) into (R)-4-tert-butyldimethylsilyloxy-2-cyclopentenone. Several acid derivatives of 7-thiaprostaglandin E1 were also prepared either by enzymatic or by chemical methods. The stereochemistry of these products was assigned on the basis of the results with chiral protected cyclopentenones and chiral ω-side chains. Some of these 7-thiaprostaglandin E1 congeners were found to exhibit more potent platelet aggregation-inhibitory activity than PGE1. The structure-activity relationship of these congeners is discussed.