Utilization of the Phenylthio Substituent as a Multipurpose Synthetic Tool. Direct Application to the Enantioselective Construction of (-)-Salsolene Oxide.

The architecturally unprecedented sesquiterpene (-)-salsolene oxide (1) has been synthesized in enantioselective fashion from (R)-(-)-carvone. Generation of the phenylthio-substituted vinyl ketene 4 is followed by intramolecular cyclization to the functionalized cyclobutanone 9. Vinyllithium addition to this intermediate proceeds in that stereocontrolled fashion which enables oxy-Cope rearrangement to operate readily under conditions of kinetic control.