Enantiospecific synthesis of sesquiterpenes from (<i style="">R</i>)-carvone. Synthesis of 3-thapsenol

Abstract

Enantiospecific synthesis of 3-thapsenol, comprising the carbon framework of a small group of sesquiterpenes containing three contiguous quaternary carbon atoms has been described. (<i style="">R</i>)-Carvone has been employed as the chiral starting material utilizing the isopropenyl group as a masked hydroxy group. A combination of alkylation, orthoester Claisen rearrangement and intramolecular diazo ketone cyclopropanation reactions has been employed for the creation of the three requisite contiguous quaternary carbon atoms.