title: Palladium-catalyzed asymmetric arylation, vinylation, and allenylation of tert-cyclobutanols via enantioselective C-C bond cleavage.
abstract: A novel enantioselective C-C bond cleavage has been achieved using palladium catalysts and chiral N,P-bidentate ligands in the asymmetric arylation, vinylation, and allenylation of tert-cyclobutanols. In these reactions, the enantioselective beta-carbon elimination of Pd(II) alcoholate formed in situ is the key step. Treatment of tert-cyclobutanols with arylating reagents in toluene in the presence of Pd(OAc)(2), a chiral ferrocene-containing N,P-bidentate ligand, and Cs(2)CO(3) affords optically active gamma-arylated ketones in excellent yields with high enantioselectivity (up to 95% ee). When vinylating reagents are used in place of arylating ones, the asymmetric vinylation also proceeds to afford optically active gamma-vinylated ketones in high yields with good to high enantioselectivity. When propargylic acetates are used, which are known to generate (sigma-allenyl)palladium complexes with Pd(0) species, asymmetric allenylation occurs to afford optically active gamma-allenylated ketones in moderate to good yields with moderate to high enantioselectivity.
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Matsumura
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Maeda
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nishimura
authors.forename: Sakae
authors.initials: S
authors.lastname: Uemura