Catalysts for Suzuki−Miyaura Coupling Processes:  Scope and Studies of the Effect of Ligand Structure

• Published in: Journal of the American Chemical Society Vol. 127; no. 13; pp. 4685 - 4696
• Main Authors: Barder, Timothy E, Walker, Shawn D, Martinelli, Joseph R, Buchwald, Stephen L
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 06.04.2005; Amer Chemical Soc
• Subjects: Boronic Acids - chemistry; Catalysis; Chemistry; Chemistry, Multidisciplinary; Crystallography, X-Ray; Exact sciences and technology; Hydrocarbons, Halogenated - chemistry; Kinetics and mechanisms; Ligands; Organic chemistry; Organometallic Compounds - chemistry; Palladium - chemistry; Phosphines - chemistry; Physical Sciences; Reactivity and mechanisms; Science & Technology; Structure-Activity Relationship; Vinyl Compounds - chemistry; ROOM-TEMPERATURE; PALLADIUM(II) COMPLEXES; CROSS-COUPLINGS; TRIARYLPHOSPHITE COMPLEXES; HINDERED ARYL CHLORIDES; AQUEOUS-MEDIA; OXIDATIVE-ADDITION; C-H BONDS; ARYLBORONIC ACIDS; HIGHLY EFFICIENT; Catalytic reaction; Tertiary phosphine; Palladium Complexes; Organic ligand; Transition metal Complexes; Complex catalyst; Experimental study; Tandem reaction; Chemical coupling; Functionalization; Reaction mechanism; Boron Organic compounds; Platinoid Complexes; Catalyst activity
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja042491j

Suzuki−Miyaura coupling reactions of aryl and heteroaryl halides with aryl-, heteroaryl- and vinylboronic acids proceed in very good to excellent yield with the use of 2-(2‘,6‘-dimethoxybiphenyl)dicyclohexylphosphine, SPhos (1). This ligand confers unprecedented activity for these processes, allowing reactions to be performed at low catalyst levels, to prepare extremely hindered biaryls and to be carried out, in general, for reactions of aryl chlorides at room temperature. Additionally, structural studies of various 1·Pd complexes are presented along with computational data that help elucidate the efficacy that 1 imparts on Suzuki−Miyaura coupling processes. Moreover, a comparison of the reactions with 1 and with 2-(2‘,4‘,6‘-triisopropylbiphenyl)diphenylphosphine (2) is presented that is informative in determining the relative importance of ligand bulk and electron-donating ability in the high activity of catalysts derived from ligands of this type. Further, when the aryl bromide becomes too hindered, an interesting C−H bond functionalization-cross-coupling sequence intervenes to provide product in high yield.