Synthesis of 1,3,4‐Oxadiazole Acyclo C‐Nucleosides Bearing 5‐Methylthio{7‐substituted‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}moieties |
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Authors: | Mamdouh Ahmed Mohamed Taha Susan Mohamed El‐Badry |
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Abstract: | Oxidative cyclization of the sugar hydrazones ( 3a‐f ) derived from {7H‐1,2,4‐triazolo1,5‐d]tetrazol‐6‐ylsulfanyl}acetic acid hydrazide ( 1 ) and aldopentoses 2a‐c or aldohexoses 2d‐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‐triazolo1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 5a‐f ). Condensative cyclization of the sugar hydrazones ( 3a‐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‐triazolo1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 11a‐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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Keywords: | {7H‐1 2 4‐Triazolo[1 5‐d]tetrazol‐6‐ylsulfanyl}acetic acid hydrazide Sugar hydrazones Cyclization 1 3 4‐Oxadiazole acyclo C‐nucleosides |
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