285127-72-2Relevant academic research and scientific papers
Isolation and identification of the intermediates during pyrazole formation of some carbohydrate hydrazone derivatives
Awad, Laila F.
, p. 34 - 42 (2007/10/03)
Reaction of the oxidation product of L-ascorbic acid, dehydro-L-ascorbic acid, with o-phenylenediamine, followed by 2,4,6-trichlorophenylhydrazine (3) afforded 3-[1-(2,4,6-trichlorophenylhydrazono)-L-threo-2,3,4-trihydroxybut-1- yl]quinoxalin-2(1H)one (4), whose structure was deduced from studying its periodate oxidation, which gave the glyoxal derivative 3-[1-(2,4,6- trichlorophenylhydrazono)glyoxal-1-yl]quinoxalin-2(1H)one (5) that upon reduction afforded 3-[1-(2,4,6-trichlorophenylhydrazono)-2-hydroxyethy-1- yl]quinoxalin-2(1H)one (6). The reaction of 5 with 3 afforded the bishydrazone 3-[1,2-bis(2,4,6-trichlorophenylhydrazono)glyoxal-1- yl]quinoxalin-2(1H)one. The reaction of 5 with acetic anhydride in pyridine afforded the 2,3-dihydrofuro[2,3-b]quinoxaline derivative 2-acetoxy-3-[2- acetyl-2-(2,4,6-trichlorophenyl)hydrazono)]-2,3-dihydrofuro[2,3- b]quinoxaline. Acetylation of 4 with acetic anhydride in pyridine afforded the acyclic diacetate intermediate 3-[3,4-di-O-acetyl-2-deoxy-1-(2,4,6- trichlorophenylhydrazono)but-2-en-1-yl]quinoxalin-2(1H)one (12), which was also obtained from the reaction of 4 with boiling acetic anhydride. Compound 12 rearranged under the reaction conditions to give the pyrazole derivatives 3-[5-(acetoxymethyl)-1-(2,4,6-trichlorophenyl)pyrazol-3-yl]quinoxalin- 2(1H)one (14) and 2-acetoxy-3-[5-(acetoxymethyl)-1-(2,4,6- trichlorophenyl)pyrazol-3-yl)]quinoxaline (15), as well as the 2,3- dihydrofuro[2,3-b]quinoxaline derivative 2-(2-acetoxyethen-2-yl)-3-[2-(2,4,6- trichlorophenyl)hydrazono]-2,3-dihydrofuro[2,3-b]quinoxaline. Acetylation of 3-[5-(hydroxymethyl)-1-(2,4,6-trichlorophenyl)pyrazol-3-yl]quinoxalin- 2(1H)one (16) with acetic anhydride in pyridine or 12 with boiling acetic anhydride afforded 15 and 16, respectively. Treatment of 4 with diluted sodium hydroxide afforded the pyrazolo[2,3-b]quinoxaline (flavazole) derivative 1-(2,4,6-trichlorophenyl)-3-(L-threo-glycerol-1-yl)pyrazolo[2,3- b]quinoxaline whose acetylation afforded the acetyl derivative 3-(2,3,4-tri- O-acetyl-L-threo-glycerol-1-yl)-1-(2,4,6-trichlorophenyl)pyrazolo[2,3- b]quinoxaline. The assigned structures were based on spectral analysis. The activity of compound 4 against hepatitis B virus has been studied. (C) 2000 Elsevier Science Ltd.
