1975 1229Synthesis of Di- and Tetra-su bstituted 1,4,5,8-Tetra -azaphenant h renes( Pyrazino 2,3-fquinoxalines)By R. Nasielski-Hinkens * and M. Benedek-Vamos, Service de Chimie Organique, Faculte des Sciences,6-Nitroquinoxalines (I) are aminated by hydroxylamine to 5-amino-6-nitroquinoxalines (11). These are reducedto 5,6-diaminoquinoxalines (111) which condense with appropriate a-dicarbonyl compounds to yield substituted1.4,5,8 -tetra - aza p h e n a n t h re n es ( IV) .Universit6 Libre de Bruxelles, 50 Avenue F. 0. Roosevelt, B-1050 Bruxelles, BelgiumONLY a few di- and tetra-substituted 1,4,5,8-tetra-azaphenanthrenes are known, despite their potentialinterest as analogues of 1,lO-phenanthroline. We reporthere a convenient synthesis of such derivatives.5,6-Dinitroquinoxaline was an attractive precursorfor the preparation of 2,3-disubstituted tetra-azaphenan-threnes.However, attempts to nitrate quinoxaline gavepoor yields of 5,6-dinitroquinoxaline and 5 of anunexpected compound, 4-nitrobenzotriazole (Scheme 1).The method described by Case and Brennan is, however,impossible to apply to the synthesis of 2,3,6,7-tetra-aryl-tetra-azaphenanthrenes, since the nitration which isinvolved will probably occur also on the aromaticsuhstituents.The direct amination of nitroaromatic cornp~unds,~-~which has been relatively little studied and never appliedsystematically, offers an alternative route to the synthesisof precursors such as (11).Exploratory experiments finally led us to adopt thefollowing sequence.4-Nitro-o-phenylenediamine is con-densed with the appropriate a-dicarbonyl compound inboiling ethanol6 or acetic acid, leading to the known2,3-disubstituted 6-nitroquinoxalines (I), which reactreadily with hydroxylamine in alkaline medium to give5 '/o 5SCHEME 1the corresponding 5-amino-6-nitroquinoxalines (11) ;these are reduced almost quantitatively to 5,6-diamino-t New compound.$ For details of Supplementary Publications see Notice to1 S. Sherif, L. Ekladious, and G. Abd Elmalek, J . praRt.a F. H. Case and J. A. Brennan, J . Amer. Chem. SOC., 1959,81,Authors No. 7 in J.C.S. Perkin I , 1974, Index issue.Chem., 1970, 812. 759.6297.quinoxalines, and further condensation with a-diketonesaffords the desired 2,3-disubstituted or 2,3,6,7-tetra-substituted 1,4,5,8-tetra-azaphenanthrenes (IV) , in over-all yield ranging from 20 to 55 based on starting nitro-phenylenediamine. Tetra-azaphenanthrenes (IV) with,Iv+iii(IV) cm,SCHEME 2 Reagents: i, RICOCOR1 in EtOH or AcOH; ii,NH,OH + KOH in EtOH or EtOH-dioxan; iii, N,H, with10 Pd-C; iv, R2COCOR2 in EtOH or AcOHthe following substituents have been synthesised :R1 = R2 = H; R1 = H, R2 = Me T, Ph t, or$-MeO*C,H, t ;R1 = R2 = Me t, Ph, or $-MeO*C,H, t (Scheme 2).EXPERIMENTALThe Experimental section is available as SupplementaryWe thank Professor R.H. Martin for his interest andPublication No. SUP 21349 (9 pp.).$Professor J. Nasielski for discussions.1412283 Received, 4th November, 19741C. C. Price and S. T. Voong, Org. Synth., Coll. Vol. 111, 1956,4 J. H. Boyer and W. Schoen, J . Amer. Chem. SOC., 1966, 78,C . Brizzi, D. Del Monte, and E. Sandri, Ann. Chim. (ItuZy),(I D. E. Burton, A. J. Lambie, D. W. J. Lane, G. T. Newbold,p. 664.423.1964, 54, 476.and A. Percival. I . Chem. SOC. (C). 1968. 1268
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