Mechanism of Rhodium-Catalyzed Carbon-Silicon Bond Cleavage for the Synthesis of Benzosilole Derivatives: A Computational Study

Rhodium-catalyzed carbon-silicon bond cleavage reaction is an efficient approach for the synthesis of silole derivates. The newly reported density functional theory method M11 is employed in order to elucidate how to cleave the inactive C(methyl)-Si bond. The computational results indicate that oxidative addition/reductive elimination pathway is favored over direct transmetallation in the C(methyl)-Si bond cleavage step. Alternatively, 1,4-rhodium-silicon exchange could take place before oxidative addition/reductive elimination. The rate-determining step for both pathways has been targeted on the initial transmetallation of 2-trimethylsilylphenyl boronic acid. The active catalytic species is a monomeric hydroxyrhodium complex, which could be regenerated from the hydrolysis of methylrhodium complex. In addition, theoretical calculations show that the hydrolyses of both aryl and vinyl intermediates are inhibited by intramolecular pi-coordinated groups.