Enantiospecific synthesis of sesquiterpenes from(R)-carvone.Synthesis of 3-thapsenol

摘要

Enantiospecific synthesis of 3-thapsenol,comprising the carbon framework of a small group of sesquiterpenes containing three contiguous quaternary carbon atoms has been described.(R)-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.