Azide/alkyne-click reaction, 213

Copper-Catalyzed Azide/Alkyne Click Reaction 213... 

Scheme 4.3 Copper(i)-catalyzed azide-alkyne click reaction in ILs.

Dabco-based ionic liquids have been recently used, together other basic and neutral ILs, in the copper(i)-catalyzed azide-alkyne click reaction (Scheme 4.3). The model cycloaddition of a sugar azide with a sugar acetylene has been carried out in ten ILs. With one exception, in all investigated ILs the reaction afforded exclusively the 1,4-disubstituted triazole, namely a triazole-linked C-dis-accharide, in high yields. 

Ding P, Wunnicke D, Steinhoff HJ, Seela F (2010) Site-directed spin-labeling of DNA by the azide-alkyne Click reaction nanometer distance measurements on 7-deaza-2 -deoxyadenosine and 2 -deox5niridine nitroxide conjugates spatially separated or linked to a dA-dT base pair. Chem Eur J 16(48) 14385-14396... 

An interesting variation of such double coupling reactions was demonstrated for the synthesis of PtBA-b-PSt-b-PEO. In this case, azide-alkyne click reaction was combined with atom transfer nitroxide radical coupling (Scheme 72). 

Hudson, R., Li, C. J., and Moores, A. 2012. Magnetic copper-iron nanoparticles as simple heterogeneous catalysts for the azide-alkyne click reaction in water. Green Chem. 14(3) 622-624. 

Scheme 9.1 Overview of click type reactions. (a) Azide/alkyne click reaction, (b) nitrile oxide cycloaddition, (c) Diels-Alder click reaction, for example, reaction of...

The copper-catalyzed azide/alkyne click reaction has found the broadest application in the modification of ROMP polymers, with the first reported example in 2004 by Binder and Kluger [13]. Since then, the copper-catalyzed click reaction has been used for the preparation of block copolymers [24, 29, 37], stars [18, 26], cycles [23], networks [25], and graft copolymers [27, 28, 38, 56, 57], as well as for end- [16] and side-chain-functionalized polymers [13, 17, 19-22, 48]. The most often used catalysts and bases for the azide/alkyne click reaction include copper(l) iodide, copper(l) bromide, trisftriphenylphosphine) copper(l) bromide, or copperfll) sulfate/sodium ascorbate as catalyst and diisopropylethylamine (DIPEA), pentamethyldiethylenetriamine (PMDETA), or 2,2 -bipyridine (bPy) as base. 

Scheme 9.4 Route to hydrogen-bonded polymers by combining ROMP and azide/alkyne click chemistry, (a) Direct polymerization approach [13, 17], ONBEs with thymine and Hamilton-receptor functionalities, 22a and b via azide/alkyne click reaction, followed by polymerization...

CopperAzide/Alkyne Click Reaction 1217... 

Tunca et al. [27, 28,38] reported in a series of papers on a multi-click approach for the preparation of brush copolymers. The backbone consisted of homopolymers, statistical polymers, or block copolymers from ONBEs with orthogonal side groups for Diels-Alder click reaction [27,28,38], azide/alkyne click reaction, [27, 28, 38] and nitroxide coupling [27]. In a grafting-to approach, maleimide-or ONBE-functionalized polymers (PEG, P BA, PMMA (56)) were attached by Diels-Alder click reaction with the anthracene groups pendant at the polymer backbone (55) (Scheme 9.8b). PCL chains were attached by an azide/alkyne click reaction, while a combination of Diels-Alder and azide/alkyne click reaction allowed the synthesis of graft copolymers with PS-/ -PEG-, PS-h-PMMA-, or PS-/ -P BA side chains. 

The azide-alkyne click reactions are useful to attach a number of polar FGs including various azobenzene moieties to the pendants of poly(l-phenyl-5-chloro-l-pentyne), (Eq. (7)) [90]. Nucleophilic substitutions of the same starting polymer result in the formation of an imidazole-functionalized, disubstituted acetylene polymer, (Eq. (8)) [91]. The degree of incorporation of the imidazole moiety is about 65%, and the product polymer exhibits good solubility in ethanol. Hydrolysis reaction of poly[l-(/w-methoxycarbonylphenyl)-l-octyne] yields a carboxy-functionalized disubstituted acetylene polymer poly[l-(/w-carboxyphenyl)-l-octyne], (Eq. 9) [92]. Hydrazine-catalyzed deprotection of poly[l-phenyl-ll-Af-benzimide-l-undecyne] affords the corresponding polyamine, which can be further ionized with hydrobromic acid to give a polyelectrolyte ammonium salt, (Eq. (10)) [93]. 

Generation of chemical patterns with photoreactive polymers photo-Diels-Alder surface anchoring followed by azide-alkyne click reaction to immobilize fluorescent dyes, (a) SPAAC strain-promoted azide-alkyne cycloaddition and (b) CuAAC Cu(l)-catalyzed azide-alkyne cycloaddition. (Source Adapted with permission from Reference [36d].)... 

Binder, W.H. and Kluger, C. (2006) Azide/alkyne- click reactions applications in material science and organic synthesis. Current Organic Chemistry, 10,1791. 

Durmaz, H., Dag, A., Erdogan, E. et al. (2010) Multiarm star block and multiarm star mixed-block copolymers via azide-alkyne click reaction. Journal of Polymer Science Part A-Polymer Chemistry, 48,99. 

Suitable crosslinking chemistiy for the hb-PPh with reactive alkynyl functionalities derived from the AB2 approach, utilizing azide-alkyne click reaction by 1,3-dipolar cycloaddition, was utilized to check the suitability of such polymers as dielectric material in microelectronics. For polymers to be used for optoelectronic... 

Scheme 5 Synthesis of highly pure block copolymers by combination of RAFT polymerization, azide-alkyne click reaction, and de-grafting, in which cleavage of grafted chains from a silica surface can be achieved by either aminolysis or radical-induced addition-fragmentation reactions (RIAFR). Adapted from Zhao et al. [20]...

Azide-Alkyne Click Reaction in Polymer Science... 

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