Amino alcohols are widely used in chemical and pharmaceutical industries, while conventional synthesis methods face drawbacks such as low selectivity and high energy consumption. Multienzyme catalysis combined with light-driven cofactor regeneration affords a platform of light-driven synthesis of chemicals, where the transfer of electrons and protons as well as the route of enzymatic reactions dominates the energy conversion efficiency and atomic economy of carbon utilization. Herein, we construct a light-driven synthesis system comprising an energy-supplying module and a multienzyme catalytic module for 2-aminoethanol synthesis from formaldehyde and ammonia. First, a S-scheme heterojunction photocatalysts with a metal–organic framework core and a bipyridine-based conjugated polymer shell are prepared as an energy-supplying module. Through synergistic intensification of proton transfer and electron transfer, the photocatalysts render cofactor (NADH) regeneration efficiency with a turnover frequency of 30.49 h–1. Second, a multienzyme catalytic module is constructed for 2-aminoethanol synthesis in the presence of NADH. Under optimal conditions, this module produces 2-aminoethanol with an average reaction rate of 76.34 μmol L–1 h–1 within 24 h. Finally, the energy-supplying module is coupled with the multienzyme catalytic module for continuous synthesis of 2-aminoethanol from formaldehyde and ammonia, generating 0.55 mmol L–1 2-aminoethanol after 4 light–dark cycles. In addition, triethanolamine (TEOA) and glucose, a biomass-derived carbon source, are both confirmed as effective electron donors for NADH regeneration and light-driven synthesis system. This work opens a pathway for the synthesis of amino alcohols and demonstrates a paradigm for the intensification of reaction processes.
Xue-Dong Li,Qing-Wen Song,Xian-Dong Lang,Yao Chang,Liang-Nian He
Graphical Heterocycle promotion : An Ag 2 O/TMG (1,1,3,3-tetramethylguanidine) promoted substrate-driven and divergent route leads to a variety of heterocycles from propargyl alcohols, CO 2 , and 2-aminoethanols with turnover numbers up to 1260. The reaction proceeds through a cascade pathway with α-alkylidene cyclic carbonate as the intermediate. Chemical valorization of CO 2 to access various value-added compounds has been a long-term and challenging objective from the viewpoint of sustainable chemistry. Herein, a one-pot three-component reaction of terminal propargyl alcohols, CO 2 , and 2-aminoethanols was developed for the synthesis of 2-oxazolidinones and an equal amount of α-hydroxyl ketones promoted by Ag 2 O/TMG (1,1,3,3-tetramethylguanidine) with a TON (turnover number) of up to 1260. By addition of terminal propargyl alcohol, the thermodynamic disadvantage of the conventional 2-aminoethanol/CO 2 coupling was ameliorated. Mechanistic investigations including control experiments, DFT calculation, kinetic and NMR studies suggest that the reaction proceeds through a cascade pathway and TMG could activate propargyl alcohol and 2-aminoethanol through the formation of hydrogen bonds and also activate CO 2 .
Oxazolidinones and α-hydroxyl ketones are two series of fine chemicals that have been generally utilized in biological, pharmaceutical, and synthetic chemistry. Herein, a AgNO 3 /ionic liquid (IL) catalytic system was developed for the simultaneous synthesis of these compounds through the atom-economical three-component reactions of propargyl alcohols, 2-aminoethanols, and CO 2 . Notably, this system behaved excellent catalytic activity with the lowermost metal loading of 0.25 mol%. Meanwhile, it is the first reported metal-catalyzed system that could efficiently work under atmospheric CO 2 pressure and be recycled at least five times. Evaluation of the green metrics proved the AgNO 3 /IL-catalyzed processes to be relatively more sustainable and greener than the other Ag-catalyzed examples. Further mechanistic investigations revealed the derivative active species of N-heterocyclic carbene (NHC) silver complexes and CO 2 adducts generated during the process. Subsequently, their reactivity in this reaction was assessed for the first time, which was finally identified as beneficial for the catalytic activity.
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