Enantioselective Approach to (−)-Hamigeran B and (−)-4-Bromohamigeran B via Catalytic Asymmetric Hydrogenation of Racemic Ketone To Assemble the Chiral Core Framework

A new strategy featuring an iridium-catalyzed asymmetric hydrogenation of a racemic ketone via dynamic kinetic resolution to generate a cyclopentanol with three contiguous stereocenters and a SmI2-promoted pinacol coupling to install the six-membered ring with correct stereochemistry has been described for the enantioselective total synthesis of (−)-hamigeran B (19 steps, 10.6% overall yield) and (−)-4-bromohamigeran B (19 steps, 12.3% overall yield).