Xiang Hui,Jianhui Shi,Jiajun Zhang,Yan Cao,Huiquan Li,Peng He,Liguo Wang
The carbonylation of amines offers a promising route for synthesizing N-substituted carbamates with high atom economy. However, conventional catalysts exhibit limited catalytic efficiency, and the underlying proton transfer mechanism remains elusive. Herein, we reported a metal-free, room-temperature strategy utilizing 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a dual hydrogen bond catalyst to synergistically activate propylamine (PA) and dimethyl carbonate (DMC). This green catalytic system achieves a 10-fold acceleration in reaction rate compared to other hydrogen bonding catalysts under mild conditions. This is enabled by dual hydrogen bonding of TBD with PA and DMC, which facilitates rapid proton transfer and stabilizes tetrahedral intermediates. Theoretical calculations confirm that the dual hydrogen bond system significantly lowers activation energy compared to single hydrogen bond analogs. Furthermore, it was revealed that the hydrogen bonding network within the product is the primary factor responsible for the sluggish reaction rate. This study demonstrates the effectiveness of a dual hydrogen bond system in accelerating the carbonylation of amines and provides a green route to access carbamates.
Xiao-Chao Chen,Tian Lan,Jian Zhu,Sibin Ying,Guang-Hui Shi,Kai-Chun Zhao,Lin Guo,Yong Lu,Ye Liu
The tripodal phosphine [ L1 , 1,1,1-tris(diphenylphosphino-methyl)ethane] was applied to control the activity, regioselectivity, and stability of the involved Pd-catalyst in anti-Markovnikov hydroaminocarbonylation of alkenes with aromatic amines for the synthesis of linear-amides. Due to the unique characters of L1 in terms of the steric bulkiness, the switching-coordination mode from tripodal phosphine to bidental one, and the robustness against moisture and oxygen, L1 conferred to Pd-catalyst with the high activity, good regioselectivity, and excellent stability for this carbonylation, leading to 44 ∼ 87 % yields of the target amides with L/B of greater than 80/20. The in situ high-pressure FT-IR analysis and the DFT calculations verified that L1 not only promoted the formation and stability of Pd II -H active species (ν ca. 1932 cm −1 ) but also facilitated the anti-Markovnikov’s addition of alkenes with Pd II -H bond due to the favorable energy level of linear intermediate ( B-1 ). In addition, since L1 can coordinate to Pd(II)-center as a bidental chelator as fulfill catalysis and then coordinate to Pd(0)-center as an tripodal pincer, Pd-catalyst was protected timely by L1 against metal-deposition (Pd 0 -black precipitation) to guarantee its stability for recycling uses for 5 runs without activity loss.
危险品化学品经营许可证（带存储）