Approaches to heterocyclic analogues of biphenylene. Part I. The reaction of 5,6-diaryl-2,3-dihydropyrazines with alcoholic alkali

Abstract

London E l 5 4LZ 2.3-Dihydro-5.6-diphenylpyrazine reacts with alcoholic alkali to form 2.3-diphenylpyrazine and 5,5'.6,6'-tetraphenyt-2,2'-bipyrazinyl, not 2,3.6,7-tetraphenyl-I ,4,5,8-tetra-azabiphenylene. 2.3- pyrazine undergoes an analogous reaction, but 2,3-dihydro-5,6-bis-(p-nitrophenyl) pyrazine yields only a n apparently polymeric material. The reaction of pp'-dinitrobibenzoyl with ethylenediamine produces not only 2,3-dihydro-5,6-bis-(p-nitropheny1)pyrazine. but also NN'-bis-(p-nitrobenzoy1)ethylenediamine.ALTHOUGH biphenylene has been extensively studied, little has been published about its heterocyclic analogues. The benzodiazabiphenylene (1) has been prepared'l and the benzocyclobutathiophen (2) is the only reported analogue without additional fused rings.The study of such compounds would be of particular interest in connection with the influence of the heteroatoms on bond structure and the stability of the fourmembered ring. (3) Ar = Ph (4) Ar = p-MeO*C,H4 (5) Ar = $-HOC,H4 (6) Ar = $-0,N.C,H4 (7) Ar = Ph (8) Ar = p-MeO*C,H, (9) Ar = p-O,N*C,H, (12) Ar = Ph (13) Ar = p-MeOC,H,The literature does, in fact, contain a reference to a compound to which a tetra-azabiphenylene structure was ascribed. Mason and Dryfoos found3 that 2,3-dihydro-5,6-diphenylpyrazine (3) reacted with alcoholic potassium hydroxide to yield mainly 2,3-diphenylpyrazine (7) together with a compound (' tetraphenyldipiazine ') to which they ascribed the molecular formula C,N,(C,H,),, presumably representing the structure (10); no attempt was made to confirm the structure. ' Tetraphenyldipiazine ' was also obtained from the dihydropyrazine under other conditions, but few experimental details were given. More recently, Burata re-ported4 the preparation of a compound identical with ' tetraphenyldipiazine ' from attempted Diels-Alder-

Chemiexcitation in the Peroxidative Metabolism of Diethylstilbestrol. Metabolic Products

“…Rep. Germany). Dihydroxybenzyl (6) was prepared from 4, 4'-dimethoxybenzyl (England and McDougall, 1971) and purified by recrystallization from ethanol-water (1:l VOU vol,.…”