Novel route for the transformation of a pyrimidine ring using hydrazides

It has been shown from X-ray structural analytical data that the reaction of 2-ethoxycarbonylmethyl-1,4,6-trimethylpyrimidinium iodide with carboxylic acid hydrazides gives pyrazolo1,5-a]pyrimidine derivatives and not the isomeric triazolo4,3-a]pyridines previously reported. This novel and previously unreported rearrangement of 1,2-dialkylpyrimidinium salts occurs via recyclization of the pyrimidine ring with inclusion of a fragment of the nucleophilic reagent into the transformation product. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 262–275, February, 2006.