Naofumi Morita

Quinoxalines derived from D-galactose and O-phenylenediamine in acidic media.

Quinoxalines derived from d-galactose with o-phenylenediamine (OPD) in acidic media under reflux were studied by using GLC and NMR measurements. Four quinoxaline derivatives were obtained from the reaction mixture, and were identical with those derived from d-glucose. The yields of 2-(D-lyxo-tetrahydroxybutyl)quinoxaline (GA-III), and the stereoisomeric derivative of GA-III, i.e., 2-(D-arabino-tetrahydroxybutyl)quinoxaline (ATBQ), were 13.2 and 5.3–, respectively. The ratio of GA-III to ATBQ derived from d-galactose was reciprocally coincident with that from d-glucose. Some proposals are made on the relationship between the isomerization of these sugars and the formation of quinoxaline derivatives.

Structural Changes of Quinoxaline Derivatives, with Special Reference to 2-(2', 3' '-Dihydroxypropyl)-3-hydroxymethylquinoxaline in Alakaline and Acidic Solutions

Conversion products of 2-(2′,3′-dihydroxypropyl)-3-hydroxymethylquinoxaline under alkaline and acidic refluxed conditions were characterized using GLC, GC-MS, HPLC, and NMR measurements.In an alkaline solution (pH 10, carbonate buffer), 2-(2′;,3′;-dihydroxypropyl)-3-methyl-quinoxaline (GA-I) and 2-(2′,3′-dihydroxypropyl)quinoxaline were produced in yields of 16% and 19%, respectively, whereas in an acidic solution (MeOH-AcOH-H20 = 4:5:2), a large amount (65%) of 3,4-dihydro-l#-pyrano[3,4-6]quinoxalin-3-yl methanol and a small amount (5%) of GA-I were obtained. These results suggest that the C-C linkage of the side chain in the quinoxaline readily splits in alkaline solutions, whereas in acidic solutions no such splitting can be observed, but condensation or dehydration occurs between hydroxyl groups of the side chains, or the hydroxymethyl group is reduced to a methyl group.