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We herein report palladium(0)-catalyzed decarboxylative cyclization of α-acyloxyketones having an allene moiety in the tether, giving various cyclohexanone derivatives. DFT calculations suggested that the reaction proceeds in the following sequence: (1) oxidative addition of the C(α)–O bond of α-acyloxyketones 1 to a palladium(0) complex; (2) insertion of the terminal allene double bond into the Pd–C(sp3) bond to form a C–C bond between the α-carbon of the carbonyl group and the β-carbon in the allene; (3) decarboxylation; and (4) reductive elimination to form a C(sp3)–C(sp) bond. The DFT calculations also rationalized why the reaction gives a 6-membered product instead of a 5- or 7-membered product. [ABSTRACT FROM AUTHOR]

A dirhodium-catalyzed, β-selective C–H amination of organosilicon compounds has been developed. Primary C(sp3)–H bonds of silylethyl groups and secondary C(sp3)–H bonds of silacycloalkanes can be selectively converted to C–N bonds at the β-position of the silicon atoms. The experimental data and theoretical calculations indicate that the strong σ-donor ability of the carbon–silicon bonds is responsible for the β-selectivity. Kinetic isotope effects clearly demonstrate that the C–H bond cleavage step is not turnover-limiting, but selectivity-determining. [ABSTRACT FROM AUTHOR]

Intermolecular aromatic C(sp2)–H amination promoted by neutral rhodium nitrenoids has been developed. The reactions proceeded with various oxygen-substituted arenes (1.5 equiv.) in a chemo- and regioselective manner. The aromatic C(sp2)–H amination took place at the para position of the oxygen substituent in the presence of benzylic C(sp3)–H bonds and/or C(sp3)–H bonds α to ethereal oxygen. [ABSTRACT FROM AUTHOR]

Direct catalytic alkynylation of N-unprotected trifluoromethyl ketimines is reported for the first time. A combination of catalytic amounts of diethylzinc and carboxylic acids promoted the reactions under proton-transfer conditions, allowing an unprecedented direct access to N-unprotected α-tetrasubstituted primary amines without additional deprotection steps. [ABSTRACT FROM AUTHOR]

A dirhodium-catalyzed, β-selective C-H amination of organosilicon compounds has been developed. Primary C(sp 3 )-H bonds of silylethyl groups and secondary C(sp 3 )-H bonds of silacycloalkanes can be selectively converted to C-N bonds at the β-position of the silicon atoms. The experimental data and theoretical calculations indicate that the strong σ-donor ability of the carbon-silicon bonds is responsible for the β-selectivity. Kinetic isotope effects clearly demonstrate that the C-H bond cleavage step is not turnover-limiting, but selectivity-determining.