Tri(alkylamino)cyclopropenium Acetate Ion Pair Catalysis for Reductive Functionalization of CO 2 with Amines and Hydrosilane to N -Formamides and N -Methylamines

作者：Xin Zou, Hui Zhao, Zhenjiang Li, Shaoju Cao, Yanqi Shi, Ziqi Liu, Xin Yuan, Na Shi, Haoyu Wang, Kai Guo · 发表于：ACS Sustainable Chemistry & Engineering · 年份：2025 · DOI：10.1021/acssuschemeng.5c09672 · 被引用次数：2 · 研究领域：Carbon dioxide utilization in catalysis、Organometallic Complex Synthesis and Catalysis、N-Heterocyclic Carbenes in Organic and Inorganic Chemistry

The catalytic reductive functionalization of CO 2 offers a sustainable strategy for mitigating greenhouse gas emissions while producing value-added chemicals. Herein, a series of strained ion pair catalysts, tri(alkylamino)cyclopropenium acetate ( TAC·AA ), was designed to facilitate hierarchical CO 2 reduction with amines using hydrosilane as the reductant. This system enables switchable transformations of CO 2 into either N -formamides (2e – reduction) or N -methylamines (6e – reduction) by tuning the reaction conditions. At elevated CO 2 pressure (0.5 MPa, 25 °C), 20 amines underwent efficient N -formylation, delivering products in quantitative yields (up to 99%). Strikingly, under reduced pressure (0.1 MPa) and elevated temperature (60 °C), 15 substrates attained complete N -methylation, achieving identical 99% yields with broad functional group tolerance. Control experiments, 1 H NMR titrations, and GC–MS analyses confirmed that the key intermediate in this transformation is the aminal species rather than formamides. A dual-pathway mechanism was proposed where CO 2 hydrosilylation generates silyl formate intermediates that either deliver formamides or undergo further reduction via aminal intermediates to methylamines, with selectivity governed by CO 2 pressure and temperature.