Polycyclic quinoxalines

This somophihc isocyanide insertion reaction is also suitable for use with hydrazines [48], arylsulfonyl chlorides [49], diaryliodonium salts [50], and Umemoto s reagent [50] (Scheme 13.22). Polycyclic quinoxalines can also be synthesized by the visible-light-induced decarboxylative radical cyclization of... 

Methylquinoxaline is reported to give a polycyclic derivative (117) related to quinoxaline orange with 2-equivalents of tetrachloro-1,2-ben zoquinone 2-(2-quinoxalino)-4,5,6,7-tetrachlorobenzo-1,3-dioxole... 

Synthesis of the other classes of polycyclic aziridines is reported in [106]. Derivatives of l,3,4,6a-tetrahydroazireno[l,2-a]pyrazines 88 and 1,1 a-dihydro-l,2-diarylazireno[l,2-a]quinoxaline 90 were obtained in the reaction of dibromides 86 with ethylenediamine 87 or 1,2-phenylenediamine 89 (Scheme 1.25). The authors showed the possibility of synthesizing dihydroazirenoquinoxalines 90 from a-bromochalcones. This can be confirmed by the following reaction of ce,/2-dihalogen ketones via dehydrobromination. 

Polycyclic azines, e.g. quinoline and quinoxaline, are grouped under the parent azine ring to which the azole is fused. 

Fused benzenoid heterocyclic systems including quinoxaline derivatives in an ether solvent are reduced by sodium to the corresponding antiaromatic doubly charged species <85JA1501>. These dianions represent a new class of charged species, viz., nitrogen-containing polycyclic anions. 

Unusual polycyclic systems are available via lithiated benzo[f>]thiophenes. 3,3 -Di(benzo[h]thienyl) (136 X = H) is converted into the 2,2 -dialdehyde (136 X = CHO), which reacts with PhCH2NH2-Na2S204, to give the pentacyclic compound 137.583 The dilithio compound 136 (X = Li) dimerizes in the presence of CuCl2, to give 138 (X = BT).584 3-Benzo[f>]thienyllithium (1 mol) reacts with quinoxaline (1 mol), to give 2-(3-benzo[f>]thienyl)-... 

Monoacylation of 2,3-diaminoquinoxalines has been achieved by reaction with an acid anhydride in THF. Under more vigorous conditions reaction of 2,3-diaminoquinoxalines with acid anhydrides results in ring closure to an imidazo[ ]quinoxaline. Similar ring closures have been carried out with aldehydes, acyl halides, formic acid, orthoesters, and urea. Polycyclic compounds have also been prepared from 2,3-diaminoquinoxaline by reaction with 1,-2-dicarbonyl compounds and 1,2-diamines, as illustrated in Scheme 7. 

Similar studies have been carried out on tetramethylpyrazine,384 quinoxaline and 2,3-dichloroquinoxaline and other azanaphthalenes,386 2-aminopyrimidine in p-xylene,386 and [zHi0]phenanthrene in biphenyl 887 and other polycyclic aromatic molecules,388 and in 1,3-diaza-azulene.389... 

Also, synthesis of aza-polycyclic aromatic compounds such as novel phenazines and quinoxalines using TSA was reported by Karami et al. (2011) (Scheme 3.7). This stimulated our interest in further studies on the chemistry of catalysts. 

Until now, several types of polycyclic aromatic nitrogen heterocycles have been known. In fact, heterocyclic synthesis plays an important role in modern life. Among the nitrogen heterocycles, quinoxaline and phenazine derivatives have attracted great interest because of their wide application in organic and medicinal chemistry. Many phenazine compounds are found in nature and are produced by bacteria. Quinoxalines are the fundamental components of several pharmacological active compounds and some antibiotics such as levomycin, echinomycin, and actinomycin (Bailly et al, 1999 Dell et al, 1975). 

In this part, the synthesis of some polycyclic aromatic nitrogen heterocyclic compounds through a convenient and economical method is reported by the use of MSA (Scheme 3.21) (Karami et al., 2011). MSA, as an inorganic solid acid, has been proved to be an efficient and heterogeneous catalyst for rapid synthesis of quinoxaline and phenazine derivatives from the condensation of o-phenylenediamines and 1,2-diketones in ethanol as solvent at room temperature in excellent yields (Scheme 3.21) (Karami et al., 2011). 

Karami, B., Khodabakhshi, S. and Nikrooz, M. 2011. Synthesis of aza-polycychc compounds Novel phenazines and quinoxalines using molybdate sulfuric acid (MSA). Polycycl. Aromat. Compd 31(2) 97-109. 

Karami, B., Nikrooz, M. and Khodabakhshi, S. 2012h. A modified synthesis of some novel polycyclic aromatic phenazines and quinoxalines by using the tungstate sulfuric acid (TSA) as a reusable catalyst under solvent-free conditions. J. Chin. Chem. Soc. 59(2) 187-192. 

The spectra of polycyclic heteroaromatics are complex and cannot be covered adequately in the space available here. Katritzky and Taylor [43] summarise the characteristic frequencies of many such systems such as quinoxalines, naphthyridines, pyridopyridazines and pyrimidotriazines. 

The Diels-Alder reaction of meso-tetraarylporphyrins with the pyrazine o-quinodimethane mainly affords the oxidized 49a-c instead of the expected chlorin adducts. The bisaddition is site specific, occurring in opposite pyr-rolic rings and leads to 51 and 52. The novel polycyclic 50a-c, 52a, and 52b result from the coupling between the P-fused quinoxaline ring and one adjacent meso-aryl group. In contrast to compounds 49a and 51a, there... 

The synthesis of fused and polycyclic derivatives of quinoxalines will not be dealt with in this chapter, except those cases where the formation of these systems occurs in one pot. This implies either the condensed parent compounds or the compounds capable, besides constructing a quinoxaline system, to annulate separate rings on various sides under the reaction conditions. 

Mamedov VA, Zhukova NA, Beschastnova TN, Gubaidullin AT, Levin YaA, Litvinov lA (2009a) Fused polycyclic nitrogen-containing heterocycles 20. Thiazolo[3,4-a]quinoxalines from 4-hydroxy-2-phenyliminothiazolidines and C-substituted 1,2-phenylenediamines. Russ Chem Bull, IntEd 58(1) 191-202. doi 10.1007/slll72-009-0029-z... 

Mamedov VA, Kalinin AA, Gubaidullin AT, Litvinov lA, Azancheev NM, Levin YaA (2004) Fused polycyclic nitrogen-containing heterocycles VI. Pyrrolo[l,2-a]quinoxalines. Russ J Org Chem 40(1) 114-123. doi 10.1023/B RUJ0.0000034919.73409.b3... 

Abu-Hashem AA, Gouda MA, Badria FA (2010) Synthesis of some new pyrimido[2, l 2,3] thiazolo[4,5- ]quinoxaline derivatives as anti-inflammatory and analgesic agents. Eur J Med Chem 45(5) 1976-1981. doi 10.1016/j.ejmech.2010.01.042 Adegoke EA, Alo B (1983) Polycyclic nitrogen compounds. Part iii. Synthesis of 3,3a-dihydrothiazolo[3,4-a]quinoxalin-4-ones. J Heterocycl Chem 20(6) 1513-1516. doi 10. 1002/jhet.5570200615... 

Ahmad AR, Mehta LK, Parrick J (1996) Synthesis of some substituted quinoxalines and polycyclic systems containing the quinoxaline nucleus. J Chem Soc, Perkin Trans 1(20) 2443-2449. doi 10.1039/P19960002443... 

SCHEME 26 Photoreaction of multichromophoric polycyclic compound in which the dicar bonyl moiety of 139 is replaced by the quinoxaline. 

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