Influence of the Substitution and Conformation of CH‐Bond‐Based Bis‐Triazole Acceptors in Anion‐Binding Catalysis

Abstract

A study on the key parameters involved in the anion-binding process and catalytic activity of the new family of CH-bond-based, anion-binding bis-triazole catalysts BisTri was carried out. The effects of substitution at the side arms and the central backbone structure of the catalyst were investigated. Electron-deficient 3,5-bis(trifluoromethyl)phenyl groups at the side arms led to the most strongly bound structures. The evaluation of differently shaped anions showed remarkable binding selectivity of the BisTri derivatives for the chloride anion. Examination of various nucleophiles in a model catalytic alkylation reaction suggested a more complex mechanism than the expected SN 1, in which the nucleophiles also participate partially in activation of the electrophile. DFT calculations were performed to investigate the relationship between the catalyst conformation and the binding affinity. Finally, in silico design and identification of a new, more efficient BisTri catalyst was accomplished.

Stereoselective and Enantiospecific Mono‐ and Bis‐C−H Azidation of Tröger Bases: Insight on Bridgehead Iminium Intermediates and Application to Anion‐Binding Catalysis

“…On the other hand, reactions proceeded smoothly under mild conditions (45 °C) in the presence of 9 a and 9 b to afford products 11 a – 11 c in good yields (55–89 %, Figure ). Long reaction times were however necessary, in line with previously reported results …”

“…Nevertheless, the ability of compounds 9 to behave as anion‐binding catalysts was tested. In fact, tritylations of primary amines and alcohols were investigated using the adduct (salt) of DMAP and tritylchloride as reagent . In the absence of compounds 9 , no reactivity was observed with amine substrates while, with benzyl alcohol, a moderate formation of 10 was noticed (28 %).…”

Substituent Effects in CH Hydrogen Bond Interactions: Linear Free Energy Relationships and Influence of Anions

“…6 Chemists are now widely using CH groups as HB donors in designed systems for anion capture 1,9–11 and catalysis. 12,13 …”

Three-center-four-electron halogen bond enables sub-ppm-level non-metallic complex catalysis

“…Despite the lower catalyst loading of 1a, such as 2.5, 1.0, 0.1, and 0.05 mol% (500 ppm), the reaction proceeded smoothly, producing reasonable yields of 5a (entries 3, 4, 5, and 6). For comparison, 1,3-bis[3,5-bis(trifluoromethyl)phenyl] thiourea (Schreiner's thiourea catalyst) 107 and 1,3-bis(1-(3,5-bis(trifluoromethyl)-phenyl)-1H-1,2,3-triazol-4-yl)benzene (mother skeleton of Mancheño's bis-triazole catalyst) 95,96,101,103,104,106,108 were examined as the representative of the H-bond based anion-binding catalysts. Both catalysts were unable to considerably accelerate the reaction to produce high yields of 5a (entries 7 and 8).…”