Enantioselective Total Synthesis of (−)-Nardoaristolone B via a

ABSTRACT: The first enantioselective total synthesis of (−)-nardoaristolone B is accomplished by the implementation of an enantio- and diastereoselective copper(I)-catalyzed conjugate addition/enolate trapping sequence and a gold(I)-catalyzed oxidative cyclization (intermolecular oxidant), employed for the first time in total synthesis. Nardoaristolone B (1) was isolated in 2013 fromNardostachys chinensis batal, a plant of the genus Nardostachys endemic of the Himalayan mountains.1 The synthesis of the racemic mixture has been recently reported.2 Closely related sesquiterpene (−)-aristolone (2) was isolated much earlier, in 1955, from the roots of Aristochia debilis3 and has been synthesized in racemic form by various research groups.4 Nardoaristolone B (1) exhibits protective activity on the injury of neonatal rat cardiomyocytes. We were intrigued by the possibility of accessing 1 and othe