Development of a Hydrogenative Reductive Amination for the Synthesis of Evacetrapib: Unexpected Benefits of Water

For the synthesis of cholesteryl ester transfer protein (CETP) inhibitor evacetrapib, a hydrogenative reductive amination was chosen to join the substituted cyclohexyl subunit to the benzazepine core. The addition of water, which suppressed undesired epimerization without affecting the rate of product formation, was key to the reaction's success. The process was scaled to produce more than 1100 kg of material.