Malononitrile with benzofuroxan

The reaction of benzofuroxan with malononitrile and amine catalysis proceeds to give 3-amino-quinoxaline-2-carbonitrile 1,4-dioxide (6). In this case, the primary adduct is stabilized by an intramolecular proton shift rather than by an elimination rcaction. " - Benzimidazoles can also be formed through this reaction (see also Houbcn-Weyl, Vol. E8a, p 303). 

Benzofuroxan (5) reacts under mild conditions with an enamine or with an aldehyde or ketone in the presence of ammonia or an amine to form mono- or disubstituted quinoxaline dioxides (151). Dark red dihydro-quinoxaline dioxides (e.g., 152) may be formed when an enamine is used which does not possess an a-hydrogen atom for elimination.381 2-Amino-substituted quinoxaline dioxides have been produced using (a) an ynamine [providing tertiary amines (153)],382 (b) chloroacetaldehyde and a primary amine [producing secondary amines (154)],9 and (c) some nitriles, e.g., malononitrile (to give the primary amine 155).382 The last reaction, however, is by no means a general one, since benzimidazoles are also produced from these substrates (see below). l-Hydroxyquinoxalin-2-one 4-oxides (156) can also be formed in several ways using (a) an a-substituted /1-ketoester (157)... 

Benzofuroxan has been proposed for use as a biochemical assay of enzymic thiol groups,438 and as a spot test for malononitrile and its derivatives, with which it forms a violet color in the presence of alkali.538... 

An extension of the Beirut reaction for the preparation of the first members of the quinoxaline 1,4-dioxideannulated crown ether series has been described (Forster et al. 1985 Niclas et al. 1985). Benzofuroxan-15-crown-5 3 in MeOH reacts with various ketones 18 in the presence of HOCH2CH2NH2 or NH3. It also reacts in DMF with malononitrile 19 in the presence of EtsN and leads to the annulated crown ethers 21a-c with the phenazine di-A-oxide moieties. In the 50 % aqueous NaOH solution with the hydroxyquinone 20, the annulated crown ether 21d with the phenazine di-A-oxide moiety is produced as well (Niclas et al. 1985) (Scheme 5.5). 

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