Facile one pot synthesis of 8-chloro-[1,2,4]triazolo[4,3-a]pyrazines via oxidative cyclisation using chloramine T

A facile and expedient one pot synthesis of 8-chloro-[1,2,4]triazolo[4,3-a]pyrazine derivatives from 2-chloro-3-hydrazinylpyrazine and aldehydes is described using chloramine T trihydrate as a safe and convenient electrocyclisation (oxidising) agent. The presence of the chloro group on pyrazine enabled us to access versatile new synthetic scaffolds by easy diversification using palladium catalysed Suzuki-Miyaura and Sonogashira cross coupling reactions. The products are obtained in high yields in short reaction time under mild conditions without the need for chromatographic purification. (C) 2015 Elsevier Ltd. All rights reserved.