Oxidative Palladium(II) Catalysis:  A Highly Efficient and Chemoselective Cross-Coupling Method for Carbon−Carbon Bond Formation under Base-Free and Nitrogenous-Ligand Conditions

• Published in: Journal of the American Chemical Society Vol. 128; no. 50; pp. 16384 - 16393
• Main Authors: Yoo, Kyung Soo, Yoon, Cheol Hwan, Jung, Kyung Woon
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 20-12-2006
• Subjects: Alkenes - chemistry; Boron - chemistry; Boronic Acids - chemistry; Carbon - chemistry; Catalysis; Chemistry; Cross-Linking Reagents - chemistry; Cyclohexanones - chemistry; Esterification; Exact sciences and technology; General and physical chemistry; Kinetics and mechanisms; Ligands; Molecular Structure; Nitrogen - chemistry; Organic chemistry; Oxidation-Reduction; Palladium - chemistry; Reactivity and mechanisms; Solvents; Temperature; Catalytic reaction; Chemoselectivity; Ligand; Palladium II; Selectivity; Chemical coupling; Stereoselectivity; Alkene; Olefin; Cyclic compound; Cross reaction; Reaction mechanism; Oxidation; Catalysis; Chemical reactivity; Ethylenic compound; Low temperature
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja063710z

We report herein the development of a general and mild protocol of oxygen-promoted Pd(II) catalysis resulting in the selective cross-couplings of alkenyl- and arylboron compounds with various olefins. Unlike most cross-coupling reactions, this new methodology works well even in the absence of bases, consequently averting undesired homo-couplings. Nitrogen-based ligands including dimethyl-phenanathroline enhance reactivities and offer a highly efficient and stereoselective methodology to overcome challenging substrate limitations. For instance, oxidative palladium(II) catalysis is effective with highly substituted alkenes and cyclic alkenes, which are known to be incompatible with other known catalytic conditions. Most examined reactions progressed smoothly to completion at low temperatures and in short times. These interesting results provide mechanistic insights and utilities for a new paradigm of palladium catalytic cycles without bases.