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.
An experimentally simple one-pot reaction, affording 1,5-disubstituted 1H-1,2,3-triazoles in good to excellent yields by combining vinyl sulfones, sodium azide and alkyl bromides, -tosylates, -mesylates or aryl amines, -iodides is reported. The organic azides, generated in situ react with vinyl sulfones in a regioselective fashion in the absence of metal ions. Unlike many of the recently reported strategies, this method is capable of generating alkyl/alkyl, alkyl/aryl and aryl/aryl containing 1,5-disubstituted 1,2,3-triazoles under simple reaction conditions.
NiCl 2 ?6H 2 O, in the presence of a wide range of amines, forms a green gel in protic solvents. UV-Vis studies indicate the initial formation of a square planar species which is transformed into tetrahedral or octahedral components. Theoretical studies indicate the presence of cis-Ni(OMe) 2 (MeOH) 4 as one of the major components of the gel. This study reveals that metallogel formation does not necessarily require synthetically designed ligands with pre-defined coordination sites.
1,4‐ and 1,5‐Disubstituted 1,2,3‐triazole scaffolds as surrogate of amide with large dipole moment have been utilized to access two isomeric naphthylthiourea‐based chemosensors 1 and 2 in appreciable overall yields. The easily synthesizable chemosensors 1 and 2 are designed to recognize anions and also to realize a comparative view on their sensing potentials. Different inorganic phosphates and a group of phosphorylated nucleosides such as ATP, ADP and AMP are selectively recognized by these chemosensors in semi aqueous system. The fluorometric study revealed that both the sensors sensed ATP selectively in CH3CN/H2O (4/1,v/v) by showing considerable increase in emission. 1,4‐Disubstituted triazole‐based sensor 1 has been established to be more effective than the 1,5‐disubstituted triazole‐based sensor 2 in selective sensing of ATP.
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.
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