CONVENIENT SYNTHETIC PATH TO ETHYL 1-ARYL-5-FORMYL-1<i>H</i>-1,2,3-TRIAZOLE-4-CARBOXYLATES AND 1-ARYL-1,5-DIHYDRO-4<i>H</i>-[1,2,3]TRIAZOLO[4,5-<i>d</i>]PYRIDAZIN-4-ONES

Abstract

A convenient method for selective synthesis of ethyl 1-aryl-5-formyl-1H-1,2,3-triazole-4-carboxylates and 1-aryl-1,5-dihydro-4H-[1,2,3]triazolo[4,5-d]pyridazin-4-ones has been developed. New ethyl 1-aryl-5-(diethoxymethyl)-1H-1,2,3-triazole-4-carboxylates were prepared by the reaction of different aryl azides and ethyl 4,4-diethoxy-3-oxobutanoate and readily converted into ethyl 1-aryl-5-formyl-1H-1,2,3-triazole-4-carboxylates in high overall yields. Such aldehydes were found to be reactive in several condensation reactions. Reaction of ethyl 1-aryl-5-formyl-1H-1,2,3-triazole-4-carboxylates and hydrazine provided 1-aryl-1,5-dihydro-4H-[1,2,3]triazolo[4,5-d]pyridazin-4-ones in excellent yields.