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‐acetoxy‐ethylmercaptan. Deblocking of 6 gave the free nucleoside 7 . Mesylation of 6 furnished the dimesylate 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 alternatively from chlorination of alcohol 6 with Ph₃P‐CCl₄. Carbomoylation of 6 led to the carbamate 20 , which gave the free nucleoside analogue 21 on deblocking. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:380–387, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20030