Highly enantioselective synthesis of both tetrahydroquinoxalines and dihydroquinoxalinones via Rh–thiourea catalyzed asymmetric hydrogenation

Highly efficient asymmetric hydrogenation of quinoxalines and quinoxalinones via Rh–thiourea complex was disclosed under batch and flow. Mechanism studies demonstrated the importance of HCl and a plausible outer-sphere mechanism during the process.