N- and C-acyclic thionuleoside analogues of 1,2,3-triazole

Cycloaddition of the azide derivative 5 with 1,4-dihydroxybutyne afforded the N-thio-acyclic nucleoside 6, which prepared alternatively from coupling of the bromo derivative 8 with 2-acetoxyethylmercaptan. Deblocking of 6 gave the free nucleoside 7. Mesylation of 6 furnished the ditnesylate 9, which gave three rearranged products 14-16 on treatment with chloride anion. These compounds might be obtained via the episulfonium. ion 10, which is subjected to nucleophilic displacement and further sulfur participation. Deblocking of 14-16 afforded the free nucleoside analogues 17-19, and their structures were confirmed by COSY, ROESY, HMQC, and HMBC NMR techniques. Compound 16 was prepared alters natively from chlorination of alcohol 6 with Ph3PCCl4. Carbomoylation of 6 led to the carbamate 20, which gave the free nucleoside analogue 21 on deblocking. (C) 2004 Wiley Periodicals, Inc.