DIAZOCINE CHEMISTRY .V. SYNTHESIS AND REARRANGEMENT OF DIBENZO(B,F)(1,4)DIAZOCINE-6,11(5H,12H)-DIONE

It has been shown that the condensation of o-phenylenediamine with diethyl phthalate, in the presence of sodium hydride, yields the dibenzo-1,4-diazocine derivative 6. Contrary to reports in the literature, this compound has never been prepared. Diazocine 6, when heated at its melting point, forms the dehydrated and ring-contracted compound 5. Base hydrolysis of 6 yields the benzimidazole derivative 2. A similar ring-contracted compound 13 (isolated as ester14) is obtained when 6 is treated with phosphorus pentachloride. The N,Nʹ-dimethyl derivative of 6 (compound 10), when treated with base, yields the zwitterionic ring-contracted compound 15, which, upon heating, is converted into the methyl o-2-(3-methylbenzimidazoyl)benzoate (16). Monobenzo-1,4-diazocine (18) was prepared from diethy succinate and o-phenylenediamine and was thermally rearranged to the ring-contracted compound 19. © 1969, American Chemical Society. All rights reserved.