Studies on Nucleoside Analogs. XXII. Reactions of Glycosyl Isothiocyanates : Syntheses of Glycosylamino-1, 2, 3-thiadiazoles and 1, 2, 4, 6-Thiatriazine-S-oxide Glycosides

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The reactions of glycosyl isothiocyanates (1a-c) with diazomethane or ethyl diazoacetate gave the corresponding glycosylamino-1, 2, 3-thiadiazoles (2a-c or 3a, b). Attempted ring transformation of 2 under thermal or basic conditions failed. Similar treatment of D-gluconyl isothiocyanate (1d) with diazomethane afforded D-gluco-pent-1-yl oxathiazolone (5d) in good yield. The reactions of 1a-c with acetoamidine or formamidine hydrochloride under basic conditions gave the corresponding N-glycosyl-N'-acetoamidino-or N-glycosyl-N'-formamidinothiocarboxamides (6a-c ; 7a, c). Subsequent treatment of 6b, c and 7a, c with thionyl chloride under basic conditions afforded the corresponding 1, 2, 4, 6-thiatriazine-S-oxide glycosides (8a-c ; 9a, c) in good yields. Attempted transformation of 8 to 1, 2, 4-triazole glycoside (10) was unsuccessful.