High yields of unsymmetrical biaryls via cross coupling of arylboronic acids with haloarenes using a modified Suzuki-Beletskaya procedure

Abstract

Unsymmetrical biaryls are obtained in high yields from cross coupling of arylboronic acids with haloarenes in the presence of a base using palladium acetate as a catalyst for reactions in aqueous ethanol at ambient temperature in the absence of oxygen.

Suzuki Polycondensation: Polyarylenes à la Carte

“…This exclusion is not only about the sensitivity of phosphine towards oxidation which may result in colloidal precipitation of Pd metal, but there is also evidence that oxygen can give rise to homocouplings of boronic acid and boronic ester monomers. [61] Homocouplings [62] would lead to a mismatch of the number of functional groups and, thus, result in a lower than possible molar mass and, of course, sequence defects in the backbone which by no means can be healed. Addition of excess boronate monomer may be indicated in such a case.…”

Recent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis

“…It is noteworthy that aryl iodides and activated aryl bromides coupled with arylboronic acids at RT using Pd(OAc) 2 in an aqueous medium. 84,85 Ligandless heterogeneous Pd catalysts can activate the C -Cl bond in aryl chlorides under the SM cross-coupling reaction conditions. 86 More importantly, with a judicious choice of the solvent system (dimethylacetamide (DMA) and water 20/1 at the optimum volumetric ratio), the homocoupling pathway of the aryl chlorides was blocked and the SM cross-coupling product was obtained selectively (Scheme 35).…”

Inhibition of Homo‐coupling of Arylboronic Acids in Ligand Free Pd(II)‐Catalyzed Suzuki Reaction

“…There is much interest in this area. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Normally, aryl iodides or other activated aryl compounds were used. When aryl bromides or aryl chlorides were used, symmetrical biaryl products from homo-coupling of the aryl boronic acids were observed.…”