Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a reductant.

Synthesis of Mesoporous PdxCu1–x/Al2O3-y Bimetallic Catalysts Via Mechanochemistry for Selective N-Formylation of Amines with CO2 and H2

A new boron-centered polymer, which is named poly-BPh(C6F5)2 (polymerized-bis(perfluorophenyl)-(phenyl)borane) was designed and synthesized, which is found to be an efficient catalyst for selective N-formylation and N-methylation of amines using CO2 as C1 building block in the presence of hydrosilanes. Milder reaction conditions (even at room temperature and 1 bar of CO2), remarkable recyclability, tolerance against a variety of functional groups and excellent yields reveal the excellent stability and catalytic activity of poly-BPh(C6F5)2. The process herein represents a simple, ecologically friendly and efficient route for CO2 chemical fixation into value-added chemicals. 

Recyclable polymerized Lewis acid poly-BPh(C6F5)2 catalyzed selective N-formylation and N-methylation of amines with carbon dioxide and phenylsilanes

The catalytic fixation of greenhouse gas CO2 has been a hot topic of research, in which the reduction and functionalization of CO2 is important for application. In present work, cheap and readily available alkanolamines were used as efficient catalysts with phenylsilanes as reducing agents to achieve the N-formylation reaction by constructing C-N bonds via the reaction between CO2 and amines (aliphatic or aromatic amines) under mild conditions (40℃and 0.1 MPa). Further studies showed that present catalytic system has wide substrates application. Mono-N-formylated compounds were obtained as main products with good to high yields for all amines. It is worthy noted that for p-aminobenzylamine containing two amino groups as substrate, both amino groups are formylated and N-formylation reaction occurs mainly in aliphatic amine with high electron cloud density. Scale-up research has been performed effectively with high conversion of amine (80%) to obtain the mono-formylated product selectively. Finally, the mechanism of the reaction between amine and CO2 is proposed via control experiments and spectra verification. Systematic mechanism studies have revealed that after polarization by polar solvent DMSO, N-methyldiethanolamine activates CO2 by forming internal salts, which are subsequently reduced by phenylsilanes to formoxysilane intermediates and finally to form N-formylated products. 

Efficient N-formylation of carbon dioxide and amines with alkanolamine as eco-friendly catalyst under mild conditions

The development of efficient, cost-effective and heterogeneous catalysts for the valorization of CO 2 to high-value chemicals is of vital importance in reducing CO 2 emissions. Herein, single-atom Zn on bipyridine-based porous organic polymer was successfully fabricated through a facile copolymerization of divinyl-bipyridine and divinyl-benzene monomers, followed by complexation with Zn(OAc) 2 . The prepared materials with different concentrations of bipyridine moieties possessed large surface areas, hierarchical porosity, and strong coordination interaction between Zn(OAc) 2 and the polymer scaffold. Catalytic evaluation demonstrated that the optimal single-atom Zn catalyst displayed extremely high catalytic performance towards the N-formylation of amines with CO 2 and PhSiH 3 . Notably, under mild reaction conditions (30 °C, 1 bar CO 2 ), a Zn loading as low as 0.5 mol‰ was sufficient for 94% yield of N-methylformanilide, with a record-high turnover frequency (TOF) of 376 h −1 compared to previously reported heterogeneous catalysts. Moreover, the solid catalyst could be easily recovered and reused for five cycles. Additionally, various amines could be efficiently transformed into corresponding formamide with moderate to high yields. The present work highlights a facile and cost-effective method for constructing highly efficient and recyclable single-atom metal catalysts for N-formylation of amines with CO 2 . • Single-atom Zn on bipyridine-functionalized porous organic polymers was facilely prepared. • Optimal single-atom Zn catalyst displayed extremely high catalytic performance. • A record-high turnover frequency (TOF) was obtained under mild conditions. • The catalyst showed excellent recycling stability and negligible Zn leaching. 

Single-atom Zn on bipyridine-functionalized porous organic polymers towards highly efficient N-formylation of amines with CO2 under mild conditions

We describe herein an efficient and catalyst-free methodology for N-formylation and N-methylation of various amines using BH3N(C2H5)3 as a reductant and CO2 as C1 source. This system is compatible with a wide range of substrates, such as aromatic secondary amines, aliphatic secondary amines, heterocyclic amines, and primary amines. The desired methylamines and formamides are obtained in excellent yields by changing the reaction solvent, temperature, and the amount of BH3N(C2H5)3. The optimum yields of methylamines and formamides are up to 99 %, which are comparable to the data using different catalysts. Moreover, it has been demonstrated by mechanistic research that CO2 was activated by inserting into B–H bonds of BH3N(C2H5)3 and formamide can be regarded as an intermediate species during the N-methylation formation.

Yun Yi

Papers

Catalyst-free hierarchical reduction of CO2 with BH3N(C2H5)3 for selective N-methylation and N-formylation of amines