| Popis: |
Oxidative cyclization of the sugar hydrazones (3 a-f ) derived from {7H-1,2,4-triazolo[1,5-d]tetrazol-6-ylsulfanyl}acetic acid hydrazide (1) and aldopentoses 2 a-c or aldohexoses 2 d-f with bromine in acetic acid in the presence of anhydrous sodium acetate, followed by acetylation with acetic anhydride gave the corresponding 2-(per-O-acetyl-alditol-l-yl)-5-methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,3,4-oxadiazoles (5 a-f ). Condensative cyclization of the sugar hydrazones (3 a-f ) by heating with acetic anhydride gave the corresponding 3-acetyl-2-(per-O-acetyl-alditol-1-yl)-2,3-dihydro-5-methylthio {7-acetyl-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,3,4-oxadiazoles (11 a-f ). De-O-acetylation of the acyclo C-nucleoside peracetates (5 and 11) with methanolic ammonia afforded the hydrazono lactones (7) and the acyclo C-nucleosides (12), respectively. The structures of new oxadiazole derivatives were confirmed by analytical and spectral data. |
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