Reactions of N-(o-nitroaryl). sarcosine esters with bases give 7-hydroxy-4-methyl---. quinoxaline-2, 3-drones as the principal products; the corresponding reactions of N-(3-nitro- 2-pyridyllsarcosine esters give l-hydroxy-4-methylpyrido [2, 3-blpyra-Fine-Z, J-diones. The significance of these results, in relation to a general mechanism for nitro-group condensations, is discussed.