SYNTHESIS OF PYRIDAZINE DERIVATIVES .28. TETRAZOLO-AZIDO ISOMERIZATIONS IN SOME FUSED TETRAZOLOPYRIDAZINES

It has been found that in certain cases azidotetrazolopyridazines can isomerize. 6-Azido-7-methyltetrazolo[1·5-b]pyridazine isomerizes into 6-azido-8-methyltetrazolo[1·5-b]pyridazine by simultaneous ring opening of the tetrazolo ring and cyclization of the azido group. Similarly, 6-azidopyrido-[3·2-d]tetrazolo[5·1-b]pyridazine isomerizes to the thermodynamically more stable 6-azidopyrido[2·3-d]tetrazolo[5·1-b]pyridazine. © 1969.