Novel hydrido-ruthenium(ii) complexes with histidine derivatives and their application in the hydrogenation of ketones

Abstract

The complexes RuHCl((R)-binap)(L-NH2) with L-NH2 = (S)-histidine-Me-ester (1), histamine (3), (S)-histidinol (4) or 1-Me-(S)-histidine-Me-ester (5), and RuHCl((S)-binap)(L-NH(2)) with L-NH2 = (S)-histidine-Me-ester (2) have been prepared in 60-81% overall yields in a one-pot, three-step procedure from the precursor RuCl2(PPh3)3. Their octahedral structures with hydride trans to chloride were deduced from their NMR spectra and confirmed by the results of a single crystal X-ray diffraction study for complex 3. Under H2 and in the presence of KOtBu, complexes 1-5 in 2-propanol form moderately active catalyst precursors for the asymmetric hydrogenation of acetophenone to 1-phenylethanol. Complex 5 is more active and enantioselective than complexes 1-4, allowing complete conversion to 1-phenylethanol in 46% e.e. (R) in 72 h at 20 degrees C under 1 MPa of H2 with substrate : catalyst : base = 2000 : 1 : 30. Complex 5, when activated, also catalyzes the hydrogenation of trans-4-phenyl-3-buten-2-one to exclusively the allyl alcohol 4-phenyl-3-buten-2-ol under 2.7 MPa of H2 at 50 degrees C in 2-propanol. This selectivity for C=O versus C=C hydrogenation is consistent with a mechanism involving the outer sphere transfer of hydride and proton to the polar bond. Further extensions to complexes with peptides with N-terminal histidine groups appear feasible on the basis of the current work.

Transition-Metal Hydride Radical Cations

“…Transition-metal hydride complexes can serve as important intermediates in the catalytic transfer of protons, hydrogen atoms, − hydrides, − or electrons − to substrates from H 2 gas. A comprehensive understanding of their chemistry is essential for explaining existing catalytic reactions and for the rational design of new ones.…”

Atomically Precise Au25(SR)18 Nanoparticles as Catalysts for the Selective Hydrogenation of α,β‐Unsaturated Ketones and Aldehydes

“…Previously, conventional supported gold nanoparticle catalysts have been demonstrated to be capable of the selective hydrogenation of a,b-unsaturated ketones; predominantly a,b-unsaturated alcohols form, but also side productssaturated ketones from C = C hydrogenation as well as saturated alcohols from further hydrogenation-have been reported. [18][19][20][21][22] Although conventional gold nanoparticles can achieve high conversion and selectivity (> 90 % for the unsaturated alcohol) in the hydrogenation of a,b-unsaturated ketones, the polydispersity of the Au nanoparticles precludes further studies on the effects of the electronic properties of the nanoparticles on the catalytic performance as well as the nature of the gold atoms at the metal-support interface. Moreover, conventional gold nanoparticles cannot achieve 100 % chemoselectivity for the unsaturated alcohol.…”

Research Advances of the Chiral Binap-Ru(II) Catalysts in Asymmetric Hydrogenation Reactions

“…2008 年, Bergens 课题组 [89] 报道可以利用原位生成 2007 年, Morris 课题组 [90] 2009 年, Bergens 课题组 [91] 再次谱学跟踪反应, 在 压影响. 随后, 他们 [96] 探索了配合物 98～99 催化亚胺 100～102 加氢的催化性能, 结果不甚理想.…”