Metal-Free Route to Carboxylated 1,4-Disubstituted 1,2,3-Triazoles from Methoxycarbonyl-Modified Vinyl Sulfone.

A metal-free alternative to the regioselective synthesis of carboxylated 1,4-disubstituted 1,2,3-triazoles (1,4-cDTs) has been accomplished. A methoxycarbonyl-substituted vinyl sulfone on reactions with organic azides resulted in the formation of 1,4-cDTs in an operationally simple route. The reaction, carried out with a variety of organic azides containing free alcohol, acid, Boc-protected amine, ester, protected sugars, long-chain alkanes, benzyl, 9-methylanthracenyl, and cholesteryl groups, was found to be general in nature, which afforded a plethora of new chemical entities; reactions of diazides generated mostly the desired and a few unexpected products. This article reports for the first time the targeted metal-free synthesis of any 1,4-disubstituted 1,2,3-triazole using the cycloaddition reactions of an appropriately functionalized vinyl sulfone.