An Asymmetric Biaryl Suzuki Cross‐Coupling Reaction: Stereogenic Benzylic Carbinols as Chiral Auxiliaries

Abstract

Asymmetric biaryl Suzuki coupling reactions were performed with various aryl‐ or naphthylhalide‐bearing enantiomerically pure benzylic alcohols and aryl‐ or naphthylboronic acids (or esters). The stereogenic benzylic alcohol was introduced by diastereoselective reduction of the arylhalide bearing a β‐keto sulfoxide. In the presence of Pd(OAc)2/CsF and dppf or PPh3 excellent yields and atropodiastereoselectivities were obtained. The absolute configurations of the biaryls were determined by X‐ray crystallography and 1H NMR NOESY experiments. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

A C3‐Symmetric Palladium Catalyst with a Phosphorus‐Based Tripodal Ligand

“…The enantiomerically pure complex was tested for the asymmetric cross-coupling reaction between 1-iodo-2-methoxynaphthalene and 1-naphthylboronic acid, which led to compound 7 with only 7 % ee. Despite the growing success of the Suzuki cross-coupling reaction for the construction of biaryls, its asymmetric variant still remains a challenge, [11][12][13] probably because of the inherent difficulty in coupling two sterically hindered arenes in a transition-metal-mediated process. Enantioselective couplings [13] have recently emerged as viable and more direct alternatives, thanks to the design of chiral ligands.…”

Transition metals in organic synthesis: Highlights for the year 2005

“…Asymmetric biaryl-coupling was observed using aryliodides having a chiral chelating functionality adjacent to the iodide [142]. Enantioselective Suzuki couplings of optically active aryliodides were described [143]. Oxidative addition to halo-diaryl was found to be faster compared to dihaloaryls [144].…”

Preparation of 4-aryl-β-carboline-3-carboxamides by Suzuki–Miyaura cross-coupling applied to a 4-iodo precursor obtained by ortho- directed lithiation

“…While little improvement was observed when the reaction was conducted in the same solvent mixture but in the presence of cesium fluoride (entry 5), the yield of 7e increased to 38% when this latter base was employed in dioxane-methanol (entry 6). Finally, using conditions described by Broutin and Colobert 12 for the efficient formation of o-substituted biaryls (palladium diacetate in the presence of dppf as ligand, dioxane-ethanol, cesium fluoride and 4 h reflux), compound 7e could be obtained in a very satisfactory 79% yield (entry 7). Application of these optimized conditions to the coupling of 4-iodo-β-carboline 3 with pyridine 4-boronic acid 6i did not, however, have any beneficial effect on the formation of compound 7i.…”