Efficient and promising asymmetric preparation of enantiopure tolvaptan via transfer hydrogenation with robust catalysts

Enantiopure tolvaptan, the first and only oral vasopressin antagonist for hyponatremia has been prepared by using an asymmetric transfer hydrogenation as a key step with HCOOH–Et3N or HCOONa–H2O as the hydrogen donor in open air. Good chemical yields with up to 99% enantioselectivity were obtained with a 1000:1 of S/C in an HCOONa–H2O system. The air and water stable catalysts provide a very promising prospect for industrial application.