Carbon Dioxide Based N-Formylation of Amines Catalyzed by Fluoride and Hydroxide Anions

We described herein a simple approach for N-formylation with CO2 and hydrosilane reducing agents. Fluoride and hydroxide salts efficiently catalyzed the reaction, principally through activation of the hydrosilanes, which led to hydrosilane reactivities comparable to those of NaBH4/LiAlH4. Consequently, the N-formylation of amines with CO2 could be achieved at room temperature and atmospheric pressure. The mechanism of these anionic catalysts contrasts that of the currently reported systems, for which activation of CO2 is the key mechanistic step. Using tetrabutylammonium fluoride as a simple ammonium salt catalyst, the N-formylated products of both aliphatic and aromatic amines could be obtained in excellent yields with high selectivities.