Catalytic Asymmetric Hydrogenation of α-Arylcyclohexanones and Total Synthesis of (-)-α-Lycorane

An efficient catalytic asymmetric hydrogenation of racemic -arylcyclohexanones with an ethylene ketal group at the 5-position of the cyclohexane ring via dynamic kinetic resolution has been developed, giving chiral -arylcyclohexanols with two contiguous stereocenters with up to 99% ee and >99:1 cis/trans-selectivity. Using this highly efficient asymmetric hydrogenation reaction as a key step, ()--lycorane was synthesized in 19.6% overall yield over 13 steps from commercially available starting material.