Applied Chemistry, Vol.4, No.2, 276-279, November, 2000
Photocyclization of Heterocyclic Hydrazones
Photochemical behavior of benzaldehyde-2-pyridylhydrazone in various condition was investigated. Irradiation of benzaldehyde-2-pyridylhydrazone at 300 nm led to the selective formation of a photoproduct(3-phenyl-s-triazolo[4,3-a]pyridine) by intramolecular cyclization. Their experimental results and theoretical considerations have shown that, in the case of the derivatives of arenealdehyde 2-pyridylhydrazone, this gave a general tendency for electrondonating groups to destabilize the hydrazone tautomers. Also it should be noted that the photochemical processes can be suggested by free radical intramolecular cyclization.