In a program in our laboratory devoted to the synthesis of heterocyclic compounds in the carbohydrate series, different heterocycles have been prepared, including imidazoles ', pyrazoles2,3, triazoles4, and isoxazolines4. In the present Note, we describe the ring transformation of D-a&in&ascorbic acid into quinoxaline derivatives through its reaction with o-phenylenediamine.
The reaction of dehydro-L-ascorbic acid with o-phenylenediamine gives a variety of products that depend upon the reaction conditions and the ratio of the reactant&ll. The condensation of dehydro-L-ascorbic acid with one mol. equiv. of o-phenylenediamine, gave the monoquinoxaline derivativeGe7. On the other hand, the reaction of two mol of o-phenylenediamine with one mol of dehydro-L-ascorbic acid was a subject for argument, as different structures5J0J1 were proposed for the reaction product. The structure proposed by Dahn and MolllO, for a quinoxaline 3-hydroxyalkyl 2-carboxylic acid anilide obtained, depended on its infrared spectrum.
We have now extended this reaction to the 5-epimer of dehydro-L-ascorbic acid, namely, D-erythro-2,3-hexodiulosono-1,Clactone.
Thus, oxidation of Darubino-ascorbic acid with an equimolar amount of p-benzoquinone in aqueous solution at room temperature, followed by reaction with two equivalents of ophenylenediamine, gave a yellow, crystalline product (4), namely, 3-(D-erythroglycerol-1-yl)quinoxaline-2-carboxylic acid o-aminoanilide, instead of the bisquinoxaline derivative proposed by Erlbach and 0hle5. The infrared spectrum of 4 showed a band in the carbonyl frequency region at 1680 cm-'.
Periodate oxidation of 4 consumed two mol of the oxidant, affording 3-formylquinoxaline-2-carboxylic acid o-aminoanilide (S), favoring the acyclic structure of its precursor. The reaction of o-phenylenediamine with dehydro-D-urubino-ascorbic acid, via the acyclic 2,3-hexodiulosonic acid (3), was supported by the fact that dehydroascorbic acid exists12 in solution as an equilibrium mixture of the 1,4lactone and the acyclic acid.
Acid hydrolysis of 3-(D-ery~taro-glycerol-l-yl)quinoxaline-2-carboxylic acid oaminoanilide (4) afforded the monoquinoxaline 6, namely, 3-(D-erytkro-glycerol-lyl)quinoxaline-2-carboxylic r_lactone. Its infrared spectrum showed the lactone band at 1760 cm--*, and the hydroxyl absorption at 3450 cm-l, with disappearance