Ammonium chloride-catalyzed green multicomponent synthesis of dihydropyrazine and tetrahydrodiazepine derivatives "on water".

This research describes a simple and efficient one-pot synthetic approach for the preparation of tetrahydrodiazepine and dihydropyrazine (or dihydroquinoxaline) derivatives in high yields in the presence of a substoichiometric amount of ammonium chloride as a green accelerator on water at 50 °C within 1-3 h.