UTILIZATION OF THE PHENYLTHIO SUBSTITUENT AS A MULTIPURPOSE SYNTHETICTOOL - DIRECT APPLICATION TO THE ENANTIOSELECTIVE CONSTRUCTION OF (-)-SALSOLENE OXIDE

The architecturally unprecedented sesquiterpene (-)-salsolene oxide (1 ) has been synthesized in enantioselective fashion from (R)-(-)-carvon e. 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 stereocont rolled fashion which enables oxy-Cope rearrangement to operate readily under conditions of kinetic control. After hydride reduction, the des ulfurization of 16 proceeds with inversion of bridgehead olefin geomet ry to deliver 17. This access route to the thermodynamically more stab le geometric arrangement permits direct entry to 1. Attention is calle d specifically to the critical 3-fold function played by a phenylthio group introduced at the outset.