Co(dppbsa)-catalyzed reductive N,N-dimethylation of nitroaromatics with CO₂ and hydrosilane

In this study, a novel half-sandwich phosphinesulfonate cobaltic complex (Co(dppbsa)) was prepared and characterized, which surprisingly enabled the chemoselective N,N-dimethylation of nitroaromatics with CO₂ using NaBAr^F₄ as the promotor and a combination of PhSiH₃ and Et₃SiH as the reductant. Further studies demonstrated that the catalytic activity for reduction of nitroaromatics and CO₂ could be modulated, respectively, by using a specific structure and composition of hydrosilanes. The semi-reduction products nitrosoarene and silyl formate are the key intermediates affording the most efficient C–N coupling for the N,N-dimethylation of nitroaromatics with CO₂.