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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 °C under solvent‐free conditions. In contrast, B(C6F5)3 shows little or no activity. 11B 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−⋅⋅⋅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. [ABSTRACT FROM AUTHOR]

BPh3 catalyzed 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 (1 atm) and PhSiH3 without solvent at 30–40 °C. A cascade reaction from 1-methyl-2-oxindole to 3,3′-methylenebis(1-methylindole) via 1-methylindole also proceeded. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) was used as a C1 source to prepare silyl formates, formamides, and aldehydes. Tetrabutylammonium acetate (TBAA) catalyzed the solvent-free N-formylation of amines with CO2 and hydrosilane to give formamides including Weinreb formamide, Me(MeO)NCHO, which was successively converted into aldehydes by one-pot reactions with Grignard reagents. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) was used as a C1 source to prepare silyl formates, formamides, and aldehydes. Tetrabutylammonium acetate (TBAA) catalyzed the solvent-free N-formylation of amines with CO2 and hydrosilane to give formamides including Weinreb formamide, Me(MeO)NCHO, which was successively converted into aldehydes by one-pot reactions with Grignard reagents. [ABSTRACT FROM AUTHOR]

The catalytic reactions of indoles with CO 2 and phenylsilane afforded indolo[3,2- b ]carbazoles, where the fused benzene ring was constructed by forming two C-H bonds and four C-C bonds with two CO 2 molecules via deoxygenative conversions. Nine-membered cyclophanes made up of three indoles and three CO 2 molecules were also obtained, where the cyclophane framework was constructed by forming six C-H bonds and six C-C bonds. These multicomponent cascade reactions giving completely different carbocycles were switched simply by choosing the solvent, acetonitrile or ethyl acetate.

BPh 3 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 CO 2 and PhSiH 3 ; these reactions proceed at 30-40 °C under solvent-free conditions. In contrast, B(C 6 F 5 ) 3 shows little or no activity. 11 B NMR spectra suggested the generation of [HBPh 3 ] - . The detailed mechanism of the BPh 3 -catalyzed N-methylation of N-methylaniline (1) with CO 2 and PhSiH 3 was studied by using DFT calculations. BPh 3 promotes the conversion of two substrates (N-methylaniline and CO 2 ) into a zwitterionic carbamate to give three-component species [Ph(Me)(H)N + CO 2 - ⋅⋅⋅BPh 3 ]. The carbamate and BPh 3 act as the nucleophile and Lewis acid, respectively, for the activation of PhSiH 3 to generate [HBPh 3 ] - , which is used to produce key CO 2 -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 [HBPh 3 ] - species., (© 2022 Wiley-VCH GmbH.)