Pyridazine and its Related Compounds. 151 Photolysis of 3-Azido-4,5-diphenyl-1H-pyrazolo[3,4-c]pyridazine in Different Solvents

Abstract

The photochemistry of 3-azidopyrazolopyridazine has been investigated. The irradiation of 3-azido-4,5-diphenyl-1H-pyrazolo[3,4-c]pyridazine 1 in various solvents brings to a photolytic nitrene intermediate, which involve into a ring- opening to give 3-substituted pyridazine derivatives. While the photolysis in toluene and/or anisole the photo attacks reaction of nitrene is faster than the ring opining to give the corresponding 3-anilinopyrazolopyridazine derivatives. The photolysis in the presence of diethyl malonate led to a mixture of three pyridazine derivatives.