Amino Acid‐Catalyzed Cascade [3+2]‐Cycloaddition/Hydrolysis Reactions Based on the Push–Pull Dienamine Platform: Synthesis of Highly Functionalized NH‐1,2,3‐Triazoles

Abstract

Cascade reactions! A practical and environmentally friendly amino acid catalyzed cascade process for the synthesis of highly substituted NH‐1,2,3‐triazoles was achieved for the first time through cascade [3+2]‐cycloaddition/hydrolysis of Hagemann's esters with p‐toluenesulfonyl azide (TsN3) in the presence of a catalytic amount of proline (see scheme).

On Water Cu@g‐C3N4 Catalyzed Synthesis of NH‐1,2,3‐Triazoles via [2+3] Cycloadditions of Nitroolefins/Alkynes and Sodium Azide

“…However, the synthesis of NH ‐1,2,3‐triazoles is fairly challenging compared to the direct synthesis of substituted triazoles . NH ‐1,2,3‐triazoles were prepared by the CAAC reaction of alkyne and TMSN 3 followed by deprotection of the TMS,, Pd‐catalyzed reactions of alkenyl bromides and sodium azide, or via multicomponent reactions, or through alkynes with NaN 3 in DMSO . It is noteworthy, that the condensation of nitroalkanes and NaN 3 or alkyl/aryl azides, is a popular method for the synthesis of NH ‐1,2,3‐triazoles or N1 substituted triazoles.…”

Organocatalytic Triazole Formation, Followed by Oxidative Aromatization: Regioselective Metal‐Free Synthesis of Benzotriazoles

“…With our previous experience,6e we first optimized the high‐yielding synthesis of functionalized bicyclic N ‐aryl‐1,2,3‐triazoles from unmodified substrates at ambient conditions. For this we initiated optimization of the organocatalytic triazole formation by screening a number of known organocatalysts for the reaction of activated cyclic enone 1 a with 0.5 to 1.5 equiv of p ‐nitrophenyl azide (4‐NO 2 C 6 H 4 N 3 ) 2 a (Table 1).…”

“…Recently, organocatalytic‐triazole formation has emerged as a powerful tool in copper‐free click chemistry 6. In 2008, we have discovered a copper‐free technology for the synthesis of highly substituted N H‐1,2,3‐triazoles from commercially available unmodified enones and activated organic azides, through domino [3+2]‐cycloaddition/hydrolysis ([3+2]‐CA/H) reactions under proline catalysis 6e. Later in 2011, Pons and co‐workers reported the clever synthesis of N ‐aryl‐1,2,3‐triazoles from unactivated ketones with aryl azides under proline catalysis 6b.…”

A General Proline‐Catalyzed Synthesis of 4,5‐Disubstituted N‐Sulfonyl‐1,2,3‐Triazoles from 1,3‐Dicarbonyl Compounds and Sulfonyl Azide

“…Recently, the groups of Ramachary, Bressy, Wang and Alves have developed a method for construction of 1,2,3‐triazoles from enolizable carbonyl compounds and aryl azides employing enamine catalysis (Scheme b). In particular, reaction of enolizable carbonyl compounds and sulfonyl azides tend to give NH‐triazole or diazo compound along with small amount of N ‐sulfonyl‐1,2,3‐triazoles . Inspired by these studies and our continuing interest in the synthesis and functionalization of N ‐sulfonyl‐1,2,3‐triazoles, we envisioned a general and efficient synthesis of 4,5‐disubstituted N ‐sulfonyl‐1,2,3‐triazoles from enolizable carbonyl compound and sulfonyl azide employing organocatalyst (Scheme c).…”