Efficient TMG catalyzed synthesis of 1,2,3-triazoles

Recent Progress on Synthesis of Functionalized 1,5-Disubstituted Triazoles

Immediately after the invention of 'Click Chemistry' in 2002, the regioselective 1,2,3- triazole scaffolds resulted from respective organic azides and terminal alkynes under Cu(I) catalysis have been well recognized as the functional heterocyclic core at the centre of modern organic chemistry, medicinal chemistry, and material sciences. This CuAAC reaction has several notable features including excellent regioselectivity, high-to-excellent yields, easy to execute, short reaction time, modular in nature, mild condition, readily available starting materials, etc. Moreover, the resulting regioselective triazoles can serve as amide bond isosteres, a privileged functional group in drug discovery and development. More than hundreds of reviews had been devoted to the 'Click Chemistry' in special reference to 1,4-disubstituted triazoles, while only little efforts were made for an opposite regioisomer i.e., 1,5-disubstituted triazole. Herein, we have presented various classical approaches for an expeditious synthesis of a wide range of biologically relevant 1,5- disubstituted 1,2,3-triazole analogues. The syntheses of such a class of diversly functionalized triazoles have emerged as a crucial investigation in the domain of chemistry and biology. This tutorial review covers the literature assessment on the development of various synthetic protocols for the functionalized 1,5-disubstituted triazoles reported during the last 12 years.

Regiospecific Synthesis of 1,4,5-Trisubstituted 1,2,3-Triazoles via Enolate–Azide Cycloaddition between 1,3-Dicarbonyl Compounds and Aryl Azides

A cycloaddition reaction at room temperature between aryl azides and 1,3-dicarbonyl compounds in the presence of potassium carbonate in dimethylsulphoxide yielded 10 4-ethoxycarbonyl-1-aryl-5-methyl-1 H-1,2,3-triazoles and seven other closely-related compounds. The 1,2,3-triazoles, nine of which are new, were obtained in good to high yields and only the 1,4-regioisomers were formed.

A general metal-free route towards the synthesis of 1,2,3-triazoles from readily available primary amines and ketones

An unprecedented approach that enables the direct and selective preparation of 1,5-disubstituted 1,2,3-triazoles from abundantly available building blocks such as primary amines, enolizable ketones and 4-nitrophenyl azide as a renewable source of dinitrogen via an organocascade process has been developed. Furthermore, this efficient methodology also enables the synthesis of fully functionalized and fused N-substituted heterocycles.

An organocatalytic azide-aldehyde [3+2] cycloaddition: high-yielding regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles

An organocatalytic azide-aldehyde [3+2] cycloaddition (organo-click) reaction of a variety of enolizable aldehydes is reported. The organo-click reaction is characterized by a high rate and regioselectivity, mild reaction conditions, easily available substrates with simple operation, and excellent yields with a broad spectrum of substrates. It constitutes an alternative to the previously known CuAAC, RuAAC, and IrAAC click reactions.

An efficient one-pot strategy for the highly regioselective metal-free synthesis of 1,4-disubstituted-1,2,3-triazoles

A simple and efficient metal-free methodology for the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles by applying a novel inverse electron-demand-1,3-dipolar cycloaddition approach has been developed.