β-Silicon-effect-promoted intermolecular site-selective C(sp³)-H amination with dirhodium nitrenes

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.