FACILE AND EFFICIENT REGIOSELECTIVE SYNTHESIS OF 1-(3′-SUBSTITUTED QUINOXALIN-2′-YL)-3-ARYL/HETEROARYL-5-METHYLPYRAZOLES

This report describes an efficient and practical approach for regioselective synthesis of 1-(3'-substituted quinoxalin-2'-yl)-3-aryl/heteroaryl-5-methylpyrazoles (3a-j). Reaction of 2-chloro-3-substituted quinoxalines (1) with 3(5)-methyl-5(3)-aryl-1H-pyrazoles (2) in the presence of sodium hydride furnished the title compounds in excellent yields with good levels of regioselectivity. The present protocol is superior to the existing method, which yielded a mixture of regioisomeric pyrazoles (I, II) and triazolo[4,3-a] quinoxalines (III). Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) to view the free supplemental file.