Direct Cyclization of o- Ethylamino nitrobenzene Derivatives

Such direct cyclizations usually occur in basic media to afford quinoxaline A-oxides. For success, C2 in the ethyl group needs to be a carbonyl entity or to be suitably activated. The following examples illustrate this valuable route to such A-oxides (and thence to quinoxalines see Section 4.6.2.1). 

44%) analogs were made similarly (or in the presence of other bases) 

In contrast, o-(2-cyano-A-methylacetamido)nitrobenzene (38) gave 1-hydroxy-4-methyl-2,3(lH,4/7)-quinoxalinedione (40), presumably by hydrolysis of the intermediate carbonitrile (39) (NaOH, H2O, reflux, 30 min 53% or EtONa, EtOH, reflux, 30 min, aqueous workup 69%).  

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