Organic Letters 2010-02-19

Palladium-catalyzed chemoselective monoarylation of hydrazides for the synthesis of [1,2,4]triazolo[4,3-a]pyridines.

Andreas Reichelt, James R Falsey, Robert M Rzasa, Oliver R Thiel, Michal M Achmatowicz, Robert D Larsen, Dawei Zhang

Index: Org. Lett. 12(4) , 792-5, (2010)

Full Text: HTML

Abstract

An efficient and convenient method for the synthesis of [1,2,4]triazolo[4,3-a]pyridines was exemplified by the synthesis of 20 analogues bearing a variety of substituents at the 3-position. The methodology involves a palladium-catalyzed addition of hydrazides to 2-chloropyridine, which occurs chemoselectively at the terminal nitrogen atom of the hydrazide, followed by dehydration in acetic acid under microwave irradiation.