Enamine–azide [2+3]-cycloaddition as a method to introduce functional groups into fluorescent dyes

Cycloaddition Reactions of Enamines

“…Baleeva et al proposed an approach for constructing diverse fluorescent dyes. [54] New derivatives of the GFP (green fluorescent protein) chromophore 162, coumarin dyes 163 and the BODIPY 164 were obtained as a result of [3 + 2] cycloaddition reaction of acyclic enamines 158-160 with aliphatic and aromatic azides 161. The reaction of triazole formation proceeds only at high temperatures in polar aprotic solvents (Scheme 50).…”

A novel strategy for the functionalization and design of 4-methylene-4H-pyran merocyaninesviaenamination and 1,8-conjugate addition

“…One of the convenient strategies for the modification of dyes is the introduction of an enamino moiety. 17 This approach, on the one hand, allows the construction of new push–pull systems and, on the other hand, the enamino moiety is a reactive fragment for further modifications. 18 For 4-methylene-4 H -pyran dyes and other merocyanines, this strategy for the synthesis of new conjugated systems has been previously unknown and can promote the development of novel directions for the design of modern materials.…”

Synthesis and Spectroscopic Properties of 1,2,3-Triazole BOPAHY Dyes and Their Water-Soluble Triazolium Salts

“…Few reports regarding 1,2,3-triazolium-linked BODIPY dyes can be found. − However, as far as we know, no reports can be found with a triazolium functionality linked directly with the BODIPY dye. 1,2,3-Triazole-linked BODIPYs are mostly obtained via transition-metal-mediated click reactions between alkyne and azide functionalities. − Alternatively, Baranov et al introduced a 1,2,3-triazole onto BODIPY via an enamine-azide [2 + 3] cycloaddition . Furthermore, other organocatalytic routes toward 1,2,3-triazoles have been developed. , In 2016, our group reported a metal-free route toward 1,2,3-triazoles starting from primary amines, enolizable ketones, and 4-nitrophenyl azide (4-NPA). , Herein, we report the metal-free synthesis of 1,2,3-triazole BOPAHY dyes starting from commercially available or easily accessible 3-ketopyrroles.…”

“…22−24 Alternatively, Baranov et al introduced a 1,2,3-triazole onto BODIPY via an enamineazide [2 + 3] cycloaddition. 25 Furthermore, other organocatalytic routes toward 1,2,3-triazoles have been developed. 26,27 In 2016, our group reported a metal-free route toward 1,2,3-triazoles starting from primary amines, enolizable ketones, and 4-nitrophenyl azide (4-NPA).…”