Structure of the reaction products from dehydroascorbic acid analogues, o-phenylenediamine, and arylhydrazines. X-Ray molecular structure of 3-[L-threo-2,3,4-triacetoxy-1-(phenylhydrazono)butyl]quinoxalin-2(1H)-one hemihydrate

Abstract

Acetylation of the product obtained from successive reaction of dehydro-L-ascorbic acid with o-phenylenediamine and phenylhydrazine gave 3-[L-threo-2,3,4-triacetoxy-1-(phenylhydrazono)butyl]quinoxalin-2(1H)-one (3) rather than the cyclic structure (4) previously assigned for the reaction product. The structure of compound (3) was confirmed based on ¹H NMR, ¹³C NMR, and X-ray analysis. Reinvestigation of the reaction of 5-phenylfuran-2,3,4(5H)-trione (6) with o-phenylenediamine and an arylhydrazine led to the isolation of two components (7) and (10). The former was found to exist in dimethyl sulphoxide solution as a tautomerie mixture of hydrazone imine and diazenyl enamine. Attempted acetylation of compound (7) afforded the furo[2,3-b]quinoxaline ring system (8).