A highly active and reusable copper(i)-tren catalyst for the “click” 1,3-dipolar cycloaddition of azides and alkynes

Abstract

The copper(I) complex [Cu(C18(6)tren)]Br 1 (C18(6)tren = tris(2-dioctadecylaminoethyl)amine) which exhibits a good stability towards aerobic conditions is a versatile, highly reactive and recyclable catalyst for the Huisgen cycloaddition of azides with terminal or internal alkynes and is a useful catalyst for the preparation of "click" dendrimers.

Preparation of 1,4-disubstituted-1,2,3-triazolo ribonucleosides by Na2CuP2O7 catalyzed azide-alkyne 1,3-dipolar cycloaddition

“…This procedure appears to be regioselective and gives only the N-1 isomer for pyrimidines and N-9 isomer for adenine ( Table 1). The structures of the nucleosides 2a-h were determined from their spectral (NMR 1 H, 13 C, and Mass) data and found to be in agreement with the literature 8d . In preliminary experiments, azido-2,3,5-tri-O-benzoylribose 16 (azidosugar) 3 was chosen for the template reaction with propargyl-uracil 2a.…”

“…Deblocking of the benzoyl protecting groups was performed using methanolic ammonia (saturated at 0°C) at room temperature and gave 1,2,3-triazole ribonucleosides 9a-h in a 40-55% yield. The structures of the nucleosides were determined from their spectral ( 1 H, 13 C NMR and Mass) data. The mechanism for this Na2CuP2O7 -catalyzed synthesis of 1,2,3-triazole ribonucleosides need much more studies, but we offer the following tentative hypothesis.…”

Ligand‐Assisted, Copper(II) Acetate‐Accelerated Azide–Alkyne Cycloaddition

“…In the past few years, several other polydentate aza-ligand frameworks have also been found to aid CuAAC reactions. [14][15][16][17][18][19] We recently found that TBTA also accelerates CuA C H T U N G T R E N N U N G (OAc) 2 -mediated AAC reactions that involve nonchelating azides. [9] In a number of reactions that proceed sluggishly under Cu-A C H T U N G T R E N N U N G (OAc) 2 -mediated conditions, yields of over 90 % were achieved in the presence of TBTA within 1 or 2 h. In this work, we investigated the acceleratory effects of other polytriazoles in CuA C H T U N G T R E N N U N G (OAc) 2 -mediated AAC reactions.…”

Well-defined copper(i) complexes for Click azide–alkyne cycloaddition reactions: one Click beyond

“…16 However, it displayed a gradual decrease in activity when reused either because of oxidation of the copper(I) centers or metal leaching. Better results were obtained with related complex 5, 17 bearing a crowded tripodal ligand to effectively protect the copper center against oxidation while keeping it highly active.…”

“…6 Nevertheless, catalysts 30 and 5 can mediate the reaction of benzyl azides and 3-hexyne (Scheme 13). 52,17 Even though these reactions are not ideal (and only one alkyne was studied), they proved that alternative activation pathways are possible for copper-catalyzed cycloadditions. It is important to note that in the presence of CuBr under similar conditions, only sluggish reactions were observed, which proves the crucial role of the ligands in this reaction.…”