Copper-Catalyzed Homocoupling of Boronic Acids: A Focus on B-to-Cu and Cu-to-Cu Transmetalations

Aude Salamé; Jordan Rio; Ilaria Ciofini; Lionel Perrin; Laurence Grimaud; Pierre-Adrien Payard

doi:10.3390/molecules27217517

Copper-Catalyzed Homocoupling of Boronic Acids: A Focus on B-to-Cu and Cu-to-Cu Transmetalations

Molecules. 2022 Nov 3;27(21):7517. doi: 10.3390/molecules27217517.

Authors

Aude Salamé¹, Jordan Rio², Ilaria Ciofini³, Lionel Perrin², Laurence Grimaud¹, Pierre-Adrien Payard²

Affiliations

¹ Laboratoire des Biomolécules (LBM), Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
² Université de Lyon, Université Claude Bernard Lyon I, CNRS, INSA, CPE, UMR 5246, ICBMS, 1 rue Victor Grignard, 69622 Villeurbanne, France.
³ École Nationale Supérieure de Chimie de Paris, Centre National de la Recherche Scientifique, Institute of Chemistry for Life and HealthSciences, PSL Research University, 75006 Paris, France.

Abstract

Controlling and understanding the Cu-catalyzed homocoupling reaction is crucial to prompt the development of efficient Cu-catalyzed cross-coupling reactions. The presence of a coordinating base (hydroxide and methoxide) enables the B-to-Cu(II) transmetalation from aryl boronic acid to Cu^IICl₂ in methanol, through the formation of mixed Cu-(μ-OH)-B intermediates. A second B-to-Cu transmetalation to form bis-aryl Cu(II) complexes is disfavored. Instead, organocopper(II) dimers undergo a coupled transmetalation-electron transfer (TET) allowing the formation of bis-organocopper(III) complexes readily promoting reductive elimination. Based on this mechanism some guidelines are suggested to control the undesired formation of homocoupling product in Cu-catalyzed cross-coupling reactions.

Keywords: Cu-catalysis; DFT; boronic acid; cross-coupling; cyclic voltammetry; homocoupling; mechanism; transmetalation.

MeSH terms

Boronic Acids*
Catalysis
Copper*

Substances

Copper
Boronic Acids

Grants and funding

J.R. thanks the MESR for a PhD fellowship. The authors are grateful to the CNRS, Chimie-Paristech-PSL, ENS-PSL, ICBMS, Université Lyon 1, and the Region Auvergne Rhone Alpes for financial support.