An efficient and convenient protocol for the synthesis of quinoxalines and dihydropyrazines via cyclization-oxidation processes using HClO4•SiO2 as a heterogeneous recyclable catalyst

A convenient and straightforward method has been developed for the synthesis of quinoxalines and dihydropyrazines (DHPs) using alpha-bromo ketones and 1,2-diamines in the presence of silica supported perchloric acid (HClO4 center dot SiO2) at room temperature. The quinoxalines and DHPs were presumably formed via cyclization-oxidation. The catalyst works under heterogeneous conditions and can be recycled. (c) 2007 Elsevier Ltd. All rights reserved.