Quinoxaline, 2,3-dichloro-, reaction

Treatment of bis-lactim ether 420 with BuLi, then with cw-l,4-dichloro-2-butene in the presence of Nal afforded 3,4,9,9n-tetrahydro-6//-pyrido[l,2-fl]pyrazin-4-one (421) with 96% diastereomeric excess (97TA1855). Reaction of l,2-diphenyl-6-methyl-quinoxaline with 1,4-dichlorobutane in THF in the presence of Na at —78°C afforded a 3 1 mixture of 4a,5-diphenyl-9-methyl-l,2,3,4-tetrahydro-4a//-pyrido[l,2-n]quinoxaline and 4-(4-chlorobutyl)-2,3-diphenyl-6-methyl-1,4-dihydroquinoxaline (98JHC1349). 

Lund and coworkers [131] pioneered the use of aromatic anion radicals as mediators in a study of the catalytic reduction of bromobenzene by the electrogenerated anion radical of chrysene. Other early investigations involved the catalytic reduction of 1-bromo- and 1-chlorobutane by the anion radicals of trans-stilhene and anthracene [132], of 1-chlorohexane and 6-chloro-l-hexene by the naphthalene anion radical [133], and of 1-chlorooctane by the phenanthrene anion radical [134]. Simonet and coworkers [135] pointed out that a catalytically formed alkyl radical can react with an aromatic anion radical to form an alkylated aromatic hydrocarbon. Additional, comparatively recent work has centered on electron transfer between aromatic anion radicals and l,2-dichloro-l,2-diphenylethane [136], on reductive coupling of tert-butyl bromide with azobenzene, quinoxaline, and anthracene [137], and on the reactions of aromatic anion radicals with substituted benzyl chlorides [138], with... 

The reaction has been extended to a,a-dichloro-o-xylene [78JOM(146)245] and 2,3-bis(bromomethyl)quinoxaline [84JCS(D)23]. In both cases the addition of Nal was found to facilitate the cycliza-tion reaction. With l,8-bis(bromomethyl)naphthalene, l,l-diiodo-3,5-naphtho-1-telluracyclohexane 7 has been obtained by the reaction with Te and Nal in 2-methoxyethanol [88JOM(338)l]. 

The synthesis of (quinoxaline-2,3-diyl)bis(aryldiazenes) 1 in high overall yields (77-84%) proceeds via reaction of benzene-1,2-diamine with l,2-dichloro-l,2-ethaiiebis(iV-arylhydra-zones) in the presence of tricthylamine and oxidation of the resultant 2,3-bis(arylhydrazono)-1,2,3,4-tetrahydroquinoxalines with iodobenzene bis(trinuoroacetate). ... 

SL1414>. Octahydropyrazinol l,2-a pyrazine was obtained in an efficient manner from 1,3-dichloro-2-propanol and an A -tosylated diethylenetriamine, and the X-ray crystal structure of this fused pyrazine was obtained <04SC845>. Finally, functionalized quinoxalines and pyrazines were prepared via a microwave-assisted reaction of aryl/heteraryl 1,2-diamines and common 1,2-diketone precursors. The formation of polymeric byproducts was suppressed <04TL4873>. 

Oxidation of the parent base with hydrogen peroxide in formic acid gives a high yield of mono-N-oxide and a little di-N-oxide N-Oxidation is assumed to proceed preferentially at the less hindered 4-nitrogen. A number of substituted benzo[/]quinoxaline 4-oxides have been prepared, the majority by oxidation of the appropriate benzo[/]quinoxaline with peracids. " Treatment of benzo[/]quinoxaline 4-oxide with phosphoryl chloride gives mainly 3-chlorobenzo[/]quinoxaline. An isomeric mono-chloride, m.p. 104-104.5°, is also isolated from this reaction which is shown by independent synthesis not to be the 2-chloro derivative. A dichloro derivative, m.p. 187-188°, of unknown structure is obtained by treatment of the parent base with chlorine in glacial acetic acid. A disubstitution product of unknown orientation and m.p. 288° is obtained by nitration of... 

Diaminobenzo[g]quinoxaline (22), prepared by the reaction of the corresponding dichloro compound with liquid ammonia, is converted into the dibenzofluorubin 23 when boiled with p-toluenesulfonic acid in... 

The reaction of quinoxalin-2,3(lJf,4/J)-dithione 60 with l.ll-dichloro-3,6,9-trioxaundecane 81c unhke the reaction of quinoxalin-2,3(lff,4fl)-dione 58a with the same reagent proceeds with the formation of a mixture of products 85 and 87 (as a result of the interaction of 1 +1 ), 86 (as a result of the interaction of 1 +2 ), and 88,89 (as a result of the interaction of 2 + 2 ). As seen horn the scheme below, four of the five formed compounds are macrocycles. The isomeric structures 85,87 and 88,89 differ in accordance with the type of the alkylation of quinoxahne systems. When l,8-dichloro-3,6-dioxaoctane 81b was used instead of l,ll-dichloro-3,6,9-trioxaundecane the process proceeded with the formation of the condensation products 2 + 2 only. In this case the macrocyclic 82 contained the two N,S-alkylated quinoxaline moieties. As a result of the interaction of quinoxalin-2,3(lH,4/J)-dithione 60 with 1,5-dichloro-3-oxaoctane 81a only the acyclic products of the S-alkylation of 1+2, 2+ 3, 3+4, and 4 + 4 composition are formed in quantitative yields (2001PS169). 

The interaction of quinoxalin-2,3(li/,4//)-dione 69 with 1,10-dibromodecane 78 and l,ll-dichloro-3,6,8-trioxaundecane 79c leads to the products of di-A -alkyla-tion-l,4-quinoxalinacyclophanes 80 and 81 (Scheme 5.17) (Htay and Meth-Cohn 1976a, b). A more recent study of the reaction of compound 69 with l,ll-dichloro-3,6,8-trioxaundecane 79c under phase-transfer catalysis conditions showed that in this case the reaction products are macrocycles of another structure with one 82 or two 83 quinoxaline structural blocks, formed as a result of di-0-alkylation and attached to each other by polyether units (Scheme 5.17) (Ferfra et al. 2005). 

Scheme 5.21 Reaction of quinoxalin-2,3(l f,4ff)-dithionite with the 1,8-dichloro-3,6-dioxaoctane...

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