DFT Study of Functional Reduction of CO 2 with BH 3 NMe 3 : The Real Role of Organic Catalyst TBD.

The detailed mechanism of transition metal-free-catalyzed monomethylation of 2-naphthyl acetonitrile ( 1a ) with CO 2 in the presence of triazabicyclodecene (TBD) and BH 3 NMe 3 was investigated using density functional theory. The C-methylation process proved to generate formaldehyde followed by the formation of the product via an alcohol rather than a methoxyborane intermediate. During the reaction, CO 2 is activated to form the TBD-CO 2 adduct and BH 3 NMe 3 is changed into TBD-BH 2 ( IM2 ) in the presence of TBD. IM2 plays a real reducing role within the system due to the unique coordination capability of the B atom. In addition to enhancing the nucleophilicity of 1a through deprotonation by t BuOK, our research also indicates that the generated t BuOH not only assists in proton transfer to generate an alcohol intermediate but also promotes the regeneration of TBD.