A novel catalytic method for the straightforward hydrogenation of carboxamides and esters to primary alcohols has been developed. Chiral modification in the ligand sphere of the well-defined Cp*Ru catalyst molecule opens up a new possibility for the development of an enantioselective hydrogenation of racemic substrates via dynamic kinetic resolution.
Hydrogenation of carbon dioxide to formate was achieved using copper (Cu) catalysts in the presence of strong organic bases including amidines and guanidines.S pecifically, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) proved to be effective for the transformation of a1 :1 mixture of hydrogen and carbon dioxide into its formate salt under increased pressure in the presence of various Cu(I) and Cu(II) saltsa t1 00 8 8C. An ovel complexd erived from copper iodide and DBU equally promoted the same reaction, indicating that DBU-Cu species are involved as real catalysts in this hydrogenation.
The utilization of polymeric amines for the hydrogenation of CO 2 to methanol via formamides was explored with a focus on a catalytic promoter, as well as a beneficial reaction medium with enhanced basicity. Branched and linear poly(ethyleneimine)s (PEIs) were efficiently formylated in the presence of a series of PN H P-pincer Ru complexes under CO 2 hydrogenation conditions at 100°C in THF. The obtained Nformylated PEI was characterized by NMR spectroscopy. The formamide units on the polymer were reduced at a higher temperature under pressurized H 2 to afford methanol and to recover [a]
The catalytic hydrogenation of carbon−oxygen bonds by copper‐based catalysts has made significant progress in the past decade. Broad carbonyl compounds, such as aldehydes, ketones, carboxylic acids and their derivatives, and CO2 have been subjected to heterogeneous and homogeneous catalytic systems. Although heterogeneous copper catalysts have been used in established industrial hydrogenation processes, recent catalyst design focusing on (i) novel supports, (ii) controlled nanostructure of copper species, and (iii) bimetallic active site in combination with copper have improved the productivity of the desired reduction products. With regard to homogeneous catalysts, phosphine‐coordinated copper complexes have been utilized in chemo‐ and enantioselective hydrogenation. In addition to the phosphorus ligand effect, several sp2‐nitrogen bases have recently been explored as beneficial promoters of CO2 hydrogenation.
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