ISSN:
0018-019X
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Reduction of 1,2-Bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzene1: Synthesis of Cyclotrisazobenzene ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaene)Na2S 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]-2H-benzotriazol (4, 55%) and the colorless 2,2′-(1,2-phenylene)di-2H-benzotriazol (5, 13%). The constitutions of 3-5 and of 6, the N-acetyl derivative of 4, were deduced from their 1H-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 1H-, 13C- and 15N-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.
Zusätzliches Material:
1 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/hlca.19850680206
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