Imidazo quinoxalines

A curious finding among certain imidazo-quinoxalines is a discrepancy in the efficacy results from the TBPS shift assay and direct measurement of chloride currents, the latter method consistently giving higher intrinsic efficacy (426). Further investigation revealed that some compounds have a biphasic dose-response curve in the chloride current assay. For example, (89)potentiates chloride current... 

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. 

Two decades after the first example of annulation of the imidazole moiety (Nispen et al. 1980) to bond c of quinoxaline under the action of dilifhium salt 43, a new procedure has been suggested in which the initial compounds are quinoxali-nones 59 (Banish and Spergel 2001 Chen et al. 2001, 2002a Hazeldine et al. 2005). Protected iV-(4-methoxybenzyl)quinoxalinones 60 are introduced into the reaction with TsMIC in THF in the presence of NaH, which leads to imidazo-quinoxaline 61 in high, sometimes quantitative, yields. The protective group is removed under the action of trifluoroacetic acid (TFA), anisole and trifluoromethanesulfonic acid (TfOH). This method is simple and enables the... 

The reaction of l-(o-methylaminophenyl)imidazole-2,5-dione 101 with ethyl formate under the action of sodium yields 1,3-dioxoimidazoquinoxaline 102, which is reduced by tin in a mixture of acetic and hydrochloric acids to give imidazo-quinoxaline 103 (Scheme 4.46) (King and Clark-Lewis 1951). 

Refluxing 2,3-dichloroquinoxaline 128a with two equivalents of aiylaminoisoxa-zolone 129a in ethanol for 48 h in the absence of bases (see Sect. 4.5.1) leads to bis (imidazo)quinoxaline system 141 (Scheme 4.63) (Poursattar et al. 2012). 

Imidazo[l,2-c]pyrimidine, 2,5,7-trichloro-nucleophilic displacement reactions, 5, 627 Imi dazo[ 1,2-a]pyrimidines pK, 3, 338 reactivity, 5, 627 synthesis, 5, 647 Imidazo[ 1,2-c]pyrimidines reactions, 5, 627 structure, 5, 610 synthesis, 5, 648-649 lmidazo[ 1,5-a]pyrimidines reactions, 5, 628 synthesis, 5, 649 lmidazo[l,5-6]pyrimidines synthesis, 5, 649-650 Imidazopyrrolopyridines bromination, 4, 506 lmidazo[4,5-6]quinoxaline nomenclature, 1, 22... 

Pyrido[ 1, 2 1,2]imidazo[4,5-b]quinoxaline nomenclature, 1, 22 2,2 -Pyridoin synthesis, 2, 337 Pyrido[ 1,2-6]indazoles synthesis, 5, 335 E ridoindoles rearrangement, 4, 508 Pyrido[a]indoles synthesis, 4, 233 Pyrido[6]indoles nomenclature, 4, 498 Pyridooxadiazolones ring contraction, 4, 149... 

Quinoxalinediamine (172) and p-methoxybenzoic acid gave 2-p-methoxy-phenyl-17/-imidazo[4,5-/]quinoxaline (174) [neat synthon (2 equiv), 210°C,... 

Dimethyl-6-methylamino-5-quinoxalinamine (175) (prepared freshly as an ethanolic solution by catalytic hydrogenation of the corresponding nitro compound) and cyanogen bromide gave 3,4,8-trimethyl-3//-imidazo-[4,5-/]quinoxalin-2-amine (176) (20°C, 3.5 h 75%) the analogous... 

Quinoxalinamine (177) and chloroketene diethyl acetal (178) gave 2-(quinox-alin-2-ylamino)imidazo[ 1,2-u]quinoxaline (180), probably via the intermediate (179) [reactants, TsOH, MeCN, 20°C, 6 h then more (177)], reflux, 4 h ... 

Amino-3-phenyl-3,4-dihydro-2(177)-quinoxalinone (181) and triphosgene gave 4-phenyl-47/-imidazo[l,5,4-< e]quinoxaline-2,5(l//, 6//)-dione (182) (EtsN, THF, 20°C, N2, until substrate gone by tic 65%) analogs Ukewise. ... 

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