Mechanistic study on ligand-controlled copper-catalyzed regiodivergent silacarboxylation of allenes with carbon dioxide and silylborane†
*ab
Abstract
Recently, Tsuji and co-workers reported a ligand controlled regiodivergent silacarboxylation of allenes with CO2 and a silylborane in the presence of a copper catalyst. Product P1 was generated in the rac-Me-DuPhos (LA) assisted system while product P2 was obtained in the PCy3 (LB) assisted system. To account for the observed regioselectivity, density functional theory (DFT) calculations have been carried out in the present study. We calculated the detailed mechanisms and analyzed electronic and steric factors in the selectivity-determining states TS3A, TS9A, TS2B, and TS5B to gain insight into the origin of the observed regioselectivity. For the LA-assisted system, the regioselectivity is predicted to be determined by the great steric effects of TS9A. The more stable geometry of TS3A causes P1 to be the major product. For the LB-assisted system, electronic effects can account for the regioselectivity. The stronger attractive interaction in TS5B compared with that in TS2B leads to the generation of P2.
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