ACID-CATALYZED BENZIDINE REARRANGEMENT OF UNSYMMETRICAL HYDRAZOAROMATICS

Acid-catalyzed benzidine rearrangements of new unsymmetrical diazanes 1-3, prepared from the reduction of corresponding diazenes 4-6, were c arried out in ethanolic solutions. The results are as follows; rearran gement of (3-carbomethoxyphenyl)(3-methoxyphenyl)diazane 1 gave 4,4'-d iamino-2-carbomethoxy-2'-methoxybiphenyl 12 (p-benzidine type) in 7.1% and 10-amino-3-methoxyphenanthridin-6(5H)-one 13, 8-amino3-methoxyphe nanthridin-6(5H)-one 14 in 7.1% and 3.4%, respectively. Product 13 and 14 were formed by the condensation reaction of primarily formed o-ben zidine and diphenyline type product, respectively. rbomethoxy-2-chloro phenyl)(4-methoxyphenyl)diazane 2 and rbomethoxy-2-methylphenyl)(4-met hoxyphenyl)diazane 3 underwent mainly disproportionations to give fiss ion amines and corresponding diazenes in about 53% and 40% yields, res pectively. The results obtained from the rearrangements of diazanes 1- 3 indirectly indicated the importance of disproportionations to unders tand the benzidine rearrangements. The structures of benzidine rearran gement products were determined by usual NMR techniques such as DEFT, 2D H-H COSY, H-C COSY, 2D NOESY, and Gaussian function multiplication.