1,2,3‐Triazoles and 1,2,3‐Triazolium Ions as Catalysts

Catalytic 1,1-Cyanoalkylation of Electron-Deficient Olefins

“…It was of interest that switching the phase-transfer catalyst from TBAB to benzyltrimethylammonium chloride, which has slightly more acidic benzylic protons, resulted in a significantly lower product yield, presumably due to less efficient 1,2-proton transfer (entry 2) . This interpretation is consistent with the observation that the reaction did not occur with 1,2,3-triazolium triflate 3 featuring strong hydrogen bond-donor ability as the catalyst (entry 3) . Subsequent optimization of the reaction conditions revealed that 10 mol % TBAB and 3 equiv of KCN were sufficient for quantitative formation of 2a (entries 4–6).…”

“…15 This interpretation is consistent with the observation that the reaction did not occur with 1,2,3-triazolium triflate 3 featuring strong hydrogen bond-donor ability as the catalyst (entry 3). 16 Subsequent optimization of the reaction conditions revealed that 10 mol % TBAB and 3 equiv of KCN were sufficient for quantitative formation of 2a (entries 4−6). While three-component coupling in diethyl ether afforded 2a with comparable efficiency and diastereoselectivity, dichloromethane appeared to be an unsuitable solvent (entries 7 and 8).…”

Enantioselective dearomatization reactions of heteroarenes by anion-binding organocatalysis

“…38 1,2,3-Triazoles are heterocycles with interesting properties such as large dipole moment ( μ = 4.38 D) 39 and highly polarizable C–H bonds, 40 what makes them promising HB-donor moieties for anion-binding catalysis. 41 The chirality in the triazole catalysts 7 is introduced by a chiral trans -1,2-diamine unit that acts as a central backbone to pre-orientate the formation of the chiral helical structure upon binding to the substrate counter-anion. Nevertheless, this central chirality is not enough to induce high level chirality transfer, given that four triazole rings are required to have a cooperative effect towards the effective formation of a chiral helical triazole-anion complex.…”