Using a Diacid Oxalic Acid as Synthon

No variation in synthon is possible in this category, but the substrate can bear a variety of substituents to afford substituted 2,3(1//,47/)-quinoxalinediones. The following examples are classified according to the general procedures used. 

4-Trifluoromethyl-l,2-benzenediamine (247) and oxalic acid (248) (as dihydrate) gave 6-trifluoromethyl-2,3(l//,4//)-quinoxalinedione (249) (neat reactants, 130°C, 3 h 87%).  

4- [2-(terf-Butoxycarbonylamino)ethyl] -1,2-benzenediamine gave 6- [2-(terf-butoxy-carbonylamino)ethyl]-2,3(l /,4/i)-quinoxalinedione (250) [neat (C02H)2 2H2O, 

Methyl 2,3-diamino-6-methylbenzoate gave methyl 6-methyl-2,3-dioxo-l,2,3,4-tetrahydro-5-quinoxalinecarboxylate (252) [(C02H)2,4M HCl, reflux, 90 min 69% note survival of the ester grouping]. 2,3-Diamino-5,6-dichlorotoluene gave 6,7-dichloro-5-methyl-2,3(l//,4//)-quinoxalinedione (253) [(C02H)2, 4M HCl, reflux, 6 h 66%], 2-Isopropylaminoaniline gave l-isopropyl-2,3(l//,4//)-quinoxalinedione (254) 

Methyl 2,3-diamino-6-methylbenzoate gave methyl 6-methyl-2,3-dioxo-l,2,3,4-tetrahydro-5-quinoxalinecarboxylate (252) [(C02H)2,4M HC1, reflux, 90 min 69% note survival of the ester grouping].506 

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