The Rich Chemistry Resulting from the 1,3‐Dipolar Cycloaddition Reactions of Enamines and Azides

Abstract

Enamines exhibit exceptionally high reactivity in their 1,3‐dipolar cycloaddition reactions with azides in comparison with other dipolarophiles. This review includes the reactions of various types of enamines with azides of different nature, including catalytic processes. The initial products of the reaction, 1,2,3‐triazolines, are generally unstable and very reactive compounds which are prone to undergo various ring transformations. This provides the background for new synthetic methods and novel reaction types. The formation of a variety of products derived from the reaction of enamines with azides such as mono‐, di‐and tri‐substituted 1,2,3‐triazoles, including N‐unsubstituted derivatives, fused, conjugated and spiro heterocycles, two types of amidines and diaminoalkenes are classified in this review according to the type of stabilization/transformation of the intermediate triazolines.

Cascade reaction based synthetic strategies targeting biologically intriguing indole polycycles

“…In particular, 1,3-dipolar cycloaddition reactions have emerged as immensely useful transformations that can be applied in cascade or domino reaction designs for rapidly building molecular complexity around a desired five-membered heterocycle. [44][45][46][47][48] In a number of cases, dipolar cycloaddition reactions deliver products with high yields and in a regio-and…”

Enamine‐Mediated Azide‐Ketone [3 + 2] Cycloaddition of Azidoperfluoroalkanes

“…The presence of copper might interfere with cellular functions and limit the application of the metal‐catalyzed cycloaddition in biological systems ,. Alternatively, metal‐free strategies (organocatalytic or base‐mediated) have emerged to provide diversely substituted triazoles, using different dipolarophiles, such as enamines or enolates from readily available carbonyl compounds or activated alkenes (Scheme b‐1d) …”

“…[16,17] Alternatively, metal-free strategies (organocata-lytic [18][19][20][21][22] or base-mediated [23][24][25][26][27] ) have emerged to provide diversely substituted triazoles, using different dipolarophiles, such as enamines or enolates from readily available carbonyl compounds or activated alkenes [28] (Scheme 1b-1d). [29][30][31][32][33] Herein we report a mild and efficient synthesis of highly functionalized 1-perfluoroalkyl-1H-1,2,3-triazoles via in situ generated enamines in the Ramachary-Bressy-Wang organocatalytic azide-ketone [3 + 2] cycloaddition (Scheme 1e). Furthermore, these perfluorinated triazoles can be transformed into 1,5-disubstituted derivatives by a simple removal of the ethoxycarbonyl group.…”

Multi‐Gram Scale Synthesis of 1,2,3‐Triazolium Ionic Liquids and Assay of Their Resistance towards Bases

“…In this paper, we present a new method for the synthesis of 1,2,3‐triazolium ionic liquids with high resistance towards bases. This pathway is inspired by a method described by Thomas and Dehaen in 2016, which affords trisubstituted 1,2,3‐triazoles from primary amines and ketones via an enamine intermediate , . The procedure is metal‐free and requires the synthesis of only one common organic azide, regardless of the compound of interest.…”

“…This pathway is inspired by a method described by Thomas and Dehaen in 2016, which affords trisubstituted 1,2,3-triazoles from primary amines and ketones via an enamine intermediate. [42,43] The procedure is metal-free and requires the synthesis of only one common organic azide, regardless of the compound of interest. This compound can thus be synthesized in bulk, while all other reagents can be obtained commercially at relatively low cost.…”