Cyclization of Conjugated Azines. Synthesis and Thermal Rearrangements of 1,8-Diaryl-4,5-diaza-3-methyl- and 3-phenyl-1,3,5,7-octatetraenes (α,β-Unsaturated Azines) to 1-(1-Methyl-3-phenyl- and -1,3-diphenyl-1-propenyl)-5-arylpyrazoles

Article abstract of DOI:10.1021/jo00348a008

Methyl- (20) and phenyl-substituted (29) α,β-unsaturated azines were prepared and subjected to thermolyses.In all cases the thermolyses reaction produced two pyrazoles (23, 24 and 32, 33, respectively), except where the azine had a terminal methylene grouping.The ratios of the pyrazoles were determined from the 1H NMR.The steric and electronic effects of the azine substituents on the ratios of the pyrazoles formed are discussed.The 13C NMR of the isolated azines and pyrazoles are reported.