Cross-Coupling of Diarylborinic Acids and Anhydrides with Arylhalides Catalyzed by a Phosphite/N-Heterocyclic Carbene Co-supported Palladium Catalyst System

Abstract

A highly efficient cross-coupling of diarylborinic acids and anhydrides with aryl chlorides and bromides has been effected by using a palladium catalyst system co-supported by a strong σ-donor N-heterocyclic carbene (NHC), N,N'-bis(2,6-diisopropylphenyl) imidazol-2-ylidene, and a strong π-acceptor phosphite, triphenylphosphite, in tert-BuOH in the present of K(3)PO(4)·3H(2)O. Unsymmetrical biaryls with a variety of functional groups could be obtained in good to excellent yields using as low as 0.01, 0.2-0.5, and 1 mol % palladium loadings for aryl bromides and activated and deactivated aryl chlorides, respectively, under mild conditions. A ligand synergy between the σ-donor NHC and the π-acceptor phosphite in the Pd/NHC/P(OPh)(3) catalytic system has been proposed to be responsible for the high efficacy to arylchlorides in the cross-coupling. A scalable and economical process has therefore been developed for synthesis of Sartan biphenyl from the Pd/NHC/P(OPh)(3) catalyzed cross-coupling of di(4-methylphenyl)borinic acid with 2-chlorobenzonitrile.

Suzuki–Miyaura coupling reactions of aryl chlorides catalyzed by a new nickel(II) σ‐aryl complex

“…[14,19,33] The proposed mechanism is shown in Fig. First, precatalyst 1 is reduced by arylboronic acid in the presence of base through sequential transmetalation and reductive elimination, prior to the main catalytical cycle, to 2 p-Me-Ph-Cl p-Me-Ph-Ph 95 [33] 3 2,5-Dimethoxy-Ph-Cl 2,5-Dimethoxy-Ph-Ph 78 [34] 4 p-MeO-Ph-Cl p-MeO-Ph-Ph 86 [33] 5 p-HOCH 2 -Ph-Cl p-HOCH 2 -Ph-Ph 59 [35] 6 o-MeO 2 C-Ph-Cl o-MeO 2 C-Ph-Ph 50 [33] 7 p-MeO 2 C-Ph-Cl p-MeO 2 C-Ph-Ph 91 [36] 8 p-OHC-Ph-Cl p-OHC-Ph-Ph 83 [36] 9 p-NC-Ph-Cl p-NC-Ph-Ph 79 [33] 10 p-PhOC-Ph-Cl p-PhOC-Ph-Ph 84 The catalytic cycle involves three sequential steps: oxidative addition, transmetalation and reductive elimination.…”

N‐Heterocyclic carbene/phosphite synergistically assisted Pd/C‐catalyzed Suzuki coupling of aryl chlorides

“…When the model reaction was run in dioxane, the yield of 3aa increased to 98% under otherwise identical conditions (Table , entry 4). We have recently reported a highly efficient homogeneous Pd/NHC/P(OPh) 3 catalyst system for Suzuki coupling of diaryl borinic acids using K 3 PO 4 .3H 2 O as base in tert ‐BuOH . Therefore, we tested alcohol solvents for the Pd/C‐IPr‐P(OPh) 3 catalyst system.…”

Recent Developments in the Suzuki-Miyaura Reaction: 2010–2014

“…Zou and co-workers reported a general protocol for SMR of aryl bromides and chlorides and diarylborinic acids and anhydrides catalyzed by an in situ -generated combination Pd/IPr/P(OPh) 3 in a 1:1:2 ratio [52]. Gao prepared a series of novel bisimidazolium pincer ligands, and 25 was used in combination with Pd(OAc) 2 for the coupling of aryl bromides using catalyst loadings as low as 0.005 mol% [53].…”