Reduktion von 1,2-bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzol: Synthese von Cyclotrisazobenzol ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaen)

✍ Scribed by Hans Hilpert; Lienhard Hoesch; André S. Dreiding

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: German
• Weight: 552 KB
• Volume: 68
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19850680206

✦ Synopsis

Reduction of 1,2‐Bis[(Z)‐(2‐nitrophenyl)‐NNO‐azoxy]benzene^1^: Synthesis of Cyclotrisazobenzene ( = (5__E__,6a__Z__,11__E__,12a__Z__,17__E__,18a__Z__)‐5,6,11,12,17,18‐Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca‐hexaene)

Na~2~S reduction of 1,2‐bis[(Z)‐(2‐nitrophenyl)‐NNO‐azoxy]benzene (2) yielded 3 deoxygenated products: the (known) red 2,2′‐((E,E)‐1,2‐phenylenbisazo)dianiline (3, 23%), the orange 2‐[2‐((E)‐2‐aminophenylazo)phenyl]‐2__H__‐benzotriazol (4, 55%) and the colorless 2,2′‐(1,2‐phenylene)di‐2__H__‐benzotriazol (5, 13%). The constitutions of 3–5 and of 6, the N‐acetyl derivative of 4, were deduced from their ^1^H‐NMR spectra (chemical shifts, couplings, and symmetry properties), and the configurations of 3, 4, and 6 at their N,N‐double bonds are assumed to be the same as in 2. Oxidation of 3 with 2 mol‐equiv. of Pb(OAc)~4~ afforded 5 (47%) and a novel, highly symmetrical macrocycle, called cyclotrisazobenzene (7, 24%). The constitution of 7 as a tribenzo‐hexaaza[12]annulene and its (E)‐configuration at the N,N‐bonds was confirmed by X‐ray analysis. The molecular symmetry expressed by the ^1^H‐, ^13^C‐ and ^15^N‐NMR spectra of 7 reveals a rapid torsional motion around the six N,C bonds. This implies that the N,N‐double bonds in the cyclic 12π‐electron system (or 24π‐electron system if the benzene rings are included) of 7 are highly localized.