open access

https://hdl.handle.net/2115/90659

Mechanism of BPh3-Catalyzed N-Methylation of Amines with CO2 and Phenylsilane : Cooperative Activation of Hydrosilane

英語

organocatalysis

2022-10-18

Wiley-Blackwell

Chemistry-A European journal

28(58)

e202202210

BPh3 catalyzes the N-methylation of secondary amines and the C-methylenation (methylene-bridge formation between aromatic rings) of N,N-dimethylanilines or 1-methylindoles in the presence of CO2 and PhSiH3; these reactions proceed at 30-40 degrees C under solvent-free conditions. In contrast, B(C6F5)(3) shows little or no activity. B-11 NMR spectra suggested the generation of [HBPh3](-). The detailed mechanism of the BPh3-catalyzed N-methylation of N-methylaniline (1) with CO2 and PhSiH3 was studied by using DFT calculations. BPh3 promotes the conversion of two substrates (N-methylaniline and CO2) into a zwitterionic carbamate to give three-component species [Ph(Me)(H)N+CO2-center dot center dot center dot BPh3]. The carbamate and BPh3 act as the nucleophile and Lewis acid, respectively, for the activation of PhSiH3 to generate [HBPh3](-), which is used to produce key CO2-derived species, such as silyl formate and bis(silyl)acetal, essential for the N-methylation of 1. DFT calculations also suggested other mechanisms involving water for the generation of [HBPh3](-) species.

学術雑誌論文

Accepted Manuscript

This is the peer reviewed version of the following article: [M. Ratanasak, T. Murata, T. Adachi, J.-y. Hasegawa, T. Ema, Chem. Eur. J. 2022, 28, e202202210.], which has been published in final form at [https://doi.org/10.1002/chem.202202210]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

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