BPh 3 catalyzes the N-methylation of secondary amines and the C-methylenation (methylene-bridge formation between aromatic rings) of N,N-dimethylanilines or 1methylindoles 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 ] À . 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. The carbamate and BPh 3 act as the nucleophile and Lewis acid, respectively, for the activation of PhSiH 3 to generate [HBPh 3 ] À , 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 ] À species.

BPh3 and PhSiH3, represented as the stars Hikoboshi and Orihime, constitute a powerful catalytic system for deoxygenative CO2 conversions. According to a Japanese legend, this couple were banished to opposite sides of the Milky Way only coming together once a year. When BPh3 and PhSiH3 come together as catalyst and reductant, N‐methylaniline undergoes N‐methylation at room temperature under CO2 and under solvent‐free conditions. The catalytic mechanism was studied by NMR measurements and DFT calculations, both of which strongly suggested the generation of [HBPh3]− as a key catalytic species. More information can be found in the Research Article by J.‐y. Hasegawa, T. Ema, and co‐workers (DOI: 10.1002/chem.202202210).