3,6-Dialkyl-1-phenyl-6-phenylazo-1,4,5,6-tetrahydropyridazine, (4+2)-Cycloadditionsprodukte aus 2-Phenylazo-1-alkenen, 2. Teil: Reaktionen

摘要

Catalytic hydrogenation of 3.6-dialkyl-1-phenyl-6-phenylazo-1.4.5.6-tetrahydropyridazines2 a-egives crystalline bisphenylhydrazones of 1.4-diketones4 a-e; in solution,4exists as a mixture of geometrical isomers due to the two phenylhydrazone functions. Reaction of2 a-fwith H2NOH yields the dioximes of 1.4-diketones5 a-f. On acid hydrolysis of2, the 6-phenylazo substituent undergoes some reactions and yields products typical of the intermediate “zwitterionic” phenyldiazene. Thus, the tetrahydropyridazine part of2 dyields 1-anilino-2.5-diisopropyl-pyrrole (9), that of2 egives 2.2.7.7-tetramethyl-3.6-octanedione monophenylhydrazone (10) which undergoes ready oxidation to 3.6-di-t-butyl-6-phenylazo-1.2-dioxan-3-ol (