Uncovering the Mechanism of the Ag(I)/Persulfate-Catalyzed Cross-Coupling Reaction of Arylboronic Acids and Heteroarenes

• Published in: Journal of the American Chemical Society Vol. 135; no. 12; pp. 4672 - 4675
• Main Authors: Patel, Niki R, Flowers, Robert A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 27-03-2013
• Subjects: Boronic Acids - chemistry; Catalysis; Oxidation-Reduction; Pyridines - chemistry; Silver - chemistry; Sulfates - chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja400712g

The catalytic cross-coupling of arylboronic acids with pyridines through single-electron oxidation provides efficient access to substituted heterocycles. Despite the importance of this reaction, very little is known about its mechanism, and as a consequence, it is unclear whether the full scope of the transformation has been realized. Here we present kinetic and spectroscopic evidence showing a high degree of complexity in the reaction system. The mechanism derived from these studies shows the activation of Ag(I) for reduction of persulfate and an off-cycle protodeboronation by the pyridine substrate. These results provide key mechanistic insights that enable control of the off-cycle process, thus providing higher efficiency and yield.