Quinoxaline di-N-oxides

The reaction of isobenzofuroxan (131) with the morpholine enamine of cyclohexanone results in a 1,4 cycloaddition to form quinoxaline-di-N-oxide 132 (777). Quinone dibenzenesulfonimide has been found to undergo... 

Quinol inol-5-sulfoni c acid, A086 Quinone, AG08 Quinone oxime, AG49 Quinonimine, AG37 Quinoxaline, AL88 Quinoxaline di-N-oxide, AL94 Quinoxaline 1,4-dioxide, AL9 ... 

The quinoxaline di-N-oxides, carbadox and olaquindox, are used as growth promoters in pigs. As both of these compounds are rapidly metabolised... 

Initial nucleophilic attack and ring opening are involved in the conversion of benzofuroxans into quinoxaline di-N-oxides by treatment with imines, enamines, carbonyl compounds, and active methylene compounds (the Beirut reaction, also see Section 3.4.1.10.1) a representative example is shown in Scheme 197 <2003EJM791, 2005H(65) 1589, CHEC-III(8.03.10)313>. 

Enamines and enolate anions react with benzofuroxan to give quinoxaline di-N-oxides (Scheme 38) (69AHCdO)l). Sydnones (274) with phenyl isocyanate give 1,2,4-triazoles (275) <76AHC(l9)l), and from (276) the Intermediate adduct (277) can be isolated (73JA8452). This is one of the few instances in which such primary cycloadducts have been isolated in the oxazole series of mesoionic compounds. 

The first report of the preparation of quinoxaline di-N-oxides from benzofuroxans was by reaction with enamines. Benzofuroxans are themselves conveniently prepared by oxidation of the appropriate o-nitroanilines with hypochlorite or by pyrolysis of the corresponding nitrophenyl azides. A variety of enamines react satisfactorily, but the less reactive morpholine enamines give higher yields and more easily isolata-ble products (Scheme 5). " ... 

The reaction between o-benzoquinone dioxime and a-diketones and a-hydroxyketones yields quinoxaline di-N-oxides, though in relatively low yields (Scheme 9). ... 

Quinoxaline di-N-oxide formation (e.g., 24) has also been achieved by reaction of the dioxime with a, 8-unsaturated ketones A further extension of this reaction is the preparation of l-hydroxyquinoxalin-2-one... 

Suter W, Rosselet A, Knusel F, Mode of action of quindoxin and substituted quinoxaline-di-N-oxides on Escherichia coli, Antimicrob. Agents Chemother. 1978 13 770-783. 

Protonation of pyrazinelV-oxides takes place at the unsubstituted ring nitrogen as revealed by examination of their UV spectra and ionization constants in water. The same holds for unsubstituted quinoxaline N-oxide and the 3-amino derivative. Pyrazine and quinoxaline di-N-oxides are protonated at one N-oxide oxygen atom (74KGS1554). 

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