DFT Study of Functional Reduction of CO2 with BH3NMe3: The Real Role of Organic Catalyst TBD.

ABSTRACT

The detailed mechanism of transition metal-free-catalyzed monomethylation of 2-naphthyl acetonitrile (1a) with CO2 in the presence of triazabicyclodecene (TBD) and BH3NMe3 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, CO2 is activated to form the TBD-CO2 adduct and BH3NMe3 is changed into TBD-BH2 (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 tBuOK, our research also indicates that the generated tBuOH not only assists in proton transfer to generate an alcohol intermediate but also promotes the regeneration of TBD.