Skip to main content

Insight into Transmetalation Enables Cobalt-Catalyzed Suzuki-Miyaura Cross Coupling

Author(s): Neely, Jamie M; Bezdek, Mate J; Chirik, Paul J

To refer to this page use:
Abstract: Among the fundamental transformations that comprise a catalytic cycle for cross coupling, transmetalation from the nucleophile to the metal catalyst is perhaps the least understood. Optimizing this elementary step has enabled the first example of a cobalt-catalyzed Suzuki-Miyaura cross coupling between aryl triflate electrophiles and heteroaryl boron nucleophiles. Key to this discovery was the preparation and characterization of a new class of tetrahedral, high-spin bis(phosphino) pyridine cobalt(I) alkoxide and aryloxide complexes, ((PNP)-P-iPr) CoOR, and optimizing their reactivity with 2-benzofuranylBPin (Pin = pinacolate). Cobalt compounds with small alkoxide substituents such as R = methyl and ethyl underwent swift transmetalation at 23 degrees C but also proved kinetically unstable toward beta-H elimination. Secondary alkoxides such as R = Pr-i or CH(Ph) Me balanced stability and reactivity. Isolation and structural characterization of the product following transmetalation, ((PNP)-P-iPr)Co(2-benzofuranyl), established a planar, diamagnetic cobalt(I) complex, demonstrating the high-and low-spin states of cobalt(I) rapidly interconvert during this reaction. The insights from the studies in this elementary step guided selection of appropriate reaction conditions to enable the first examples of cobalt-catalyzed C-C bond formation between neutral boron nucleophiles and aryl triflate electrophiles, and a model for the successful transmetalation reactivity is proposed.
Publication Date: 28-Dec-2016
Citation: Neely, Jamie M, Bezdek, Mate J, Chirik, Paul J. (2016). Insight into Transmetalation Enables Cobalt-Catalyzed Suzuki-Miyaura Cross Coupling. ACS CENTRAL SCIENCE, 2 (935 - 942. doi:10.1021/acscentsci.6b00283
DOI: doi:10.1021/acscentsci.6b00283
ISSN: 2374-7943
EISSN: 2374-7951
Pages: 935 - 942
Type of Material: Journal Article
Journal/Proceeding Title: ACS CENTRAL SCIENCE
Version: Final published version. This is an open access article.

Items in OAR@Princeton are protected by copyright, with all rights reserved, unless otherwise indicated.