Highlights on the General Preference for Multi-Over Mono-Coupling in the Suzuki–Miyaura Reaction
Carlos F. R. A. C. Lima,
Marco A. L. Lima,
J. Ricardo M. Pinto,
M. Gabriela T. C. Ribeiro,
Artur M. S. Silva,
Luís M. N. B. F. Santos
Affiliations
Carlos F. R. A. C. Lima
CIQUP, Institute of Molecular Sciences (IMS)—Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
Marco A. L. Lima
Institut für Anorganische Chemie I, Universität Ulm Albert-Einstein-Allee 11, 89081 Ulm, Germany
J. Ricardo M. Pinto
LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua Campo Alegre s/n, 4169-007 Porto, Portugal
M. Gabriela T. C. Ribeiro
LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua Campo Alegre s/n, 4169-007 Porto, Portugal
Artur M. S. Silva
LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
Luís M. N. B. F. Santos
CIQUP, Institute of Molecular Sciences (IMS)—Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
A systematic synthetic study was performed to explain the usual trend in selectivity towards multi-coupling, over mono-coupling, in Suzuki–Miyaura reactions. This preference was observed under different reaction conditions: for various halobenzenes, using substituents on the boronic acid, and changing the catalyst and temperature. Moreover, this reaction selectivity was found to increase for more reactive systems towards oxidative addition and more diluted media. The results constitute experimental evidence that the formation of the totally substituted coupling product is kinetically favoured by a reaction path location—the proximity between the regenerated catalyst and the newly formed coupling intermediate promotes the subsequent reaction.