(4+2)-Cycloadditionen von intermediärem 1-Phenyl-1-phenylazo-äthylen (α-Phenylazo-styrol)

摘要

1-Phenyl-1-phenylazoethylene (α-phenylazostyrene,2) cannot be isolated, as, functioning both as a heterodiene and a dienophile, it reacts to its (4+2)-cyclodimer, 1,3,6-triphenyl-6-phenylazo-1,4,5,6-tetrahydropyridazine (3). In the presence of the competing dienophile 3-buten-2-one (4) the intermediate2is partially trapped to 6-acetyl-1,3-diphenyl-1,4,5,6-tetrahydropyridazine (5)