181219-01-2Relevant articles and documents
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
A heterofunctional ligand approach for the preparation of high connectivity coordination polymers: Combining a "bridge" and "pillar" in one ligand
Al-Fayaad, Hydar A.,Athukorala Arachchige, Kasun S.,Clegg, Jack K.
, p. 5310 - 5315 (2020/09/03)
Two of the most successful strategies for the preparation of three-dimensional coordination polymers and MOFs are reticular synthesis and pillaring. Here we present a new approach which combines aspects of both of these by employing a heterofunctional dicarboxylic and dipyridyl ligand, 2,5-di(pyridin-4-yl)terephthalic acid (H2L). The reaction of H2L with zinc(ii) produces a non-interpenetrated 3D coordination polymer [ZnL(H2O)]n. This journal is
para-Selective C?H Borylation of (Hetero)Arenes by Cooperative Iridium/Aluminum Catalysis
Yang, Lichen,Semba, Kazuhiko,Nakao, Yoshiaki
supporting information, p. 4853 - 4857 (2017/04/11)
para-Selective C?H borylation of benzamides and pyridines has been achieved by cooperative iridium/aluminum catalysis. A combination of iridium catalysts commonly employed for arene C?H borylation and bulky aluminum-based Lewis acid catalysts provides an unprecedented strategy for controlling the regioselectivity of C?H borylation to give variously substituted (hetero)arylboronates, which are versatile synthetic intermediates for complex multi-substituted aromatic compounds.
