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.

Regioselectivity of vinyl sulfone based 1,3-dipolar cycloaddition reactions with sugar azides by computational and experimental studies.

DFT (M06-L) calculations on the transition state for the 1,3-dipolar cycloadditions between substituted vinyl sulfones with sugar azide have been reported in conjunction with new experimental results, and the origin of reversal of regioselectivity has been revealed using a distortion/interaction model. This study provides the scientific justification for combining organic azides with two different types of vinyl sulfones for the preparation of 1,5-disubstituted 1,2,3-triazoles and 1,4-disubstituted triazolyl esters under metal-free conditions.

A general route to mono- and disubstituted divinyl sulfones: acyclic Michael acceptors for the synthesis of polyfunctionalized cyclic sulfones.

Nucleophilic C-S bond formation using easily available ß-hydroxysulfonate derivatives allowed direct access to new mono- and disubstituted divinyl sulfones. Our strategy uses thioethanol (HSCH(2)CH(2)OH) and its analogues such as HSCH(2)CH(Y)OH generated in situ. The strategy also allows the synthesis of modified divinyl sulfones attached to chiral appendages like carbohydrates. Bis-heteronucleophilic Michael addition reactions with 1 equiv of a primary amine afforded new generations of S,S-dioxothiomorpholine derivatives known for their therapeutic applications. Further synthetic manipulations of some of these cyclic compounds led to the synthesis of novel bicyclic derivatives.