1481-93-2Relevant articles and documents
Enantioselective reduction of prochiral ketones by chromium(II) complexes with amino acid ligands as the source of chirality
Patonay,Hajdu,Jeko,Levai,Micskei,Zucchi
, p. 1373 - 1374 (1999)
Prochiral ketones were reduced to enantiomerically enriched secondary alcohols by Cr(II)[L-amino acid] complexes in good yields and moderate enantioselectivity.
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Eguchi
, p. 653,654,655 (1978)
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Half-sandwich Ru (II) complexes containing (N, O) Schiff base ligands: Catalysts for base-free transfer hydrogenation of ketones
Satheesh,Sathish Kumar, Pushpanathan N.,Kumara, P. Raghavendra,Karvembu, Ramasamy,Hosamani, Amar,Nethaji
, (2019)
Two new half-sandwich Ru (II)(p-cymene) complexes (1 and 2) containing dopamine-based (N, O) Schiff base ligands (L1H and L2H) were synthesized and characterized by FT-IR, UV–Visible and 1H & 13C NMR spectral techniques, and elemental analyses. The spectroscopic and analytical data revealed monobasic bidentate coordination of the ligands with Ru ion. The molecular structures of L1H, L2H and 2 were further confirmed by single crystal X-ray diffraction study. Complexes 1 and 2?have been employed as catalysts in the transfer hydrogenation of ketones using 2-propanol as a hydrogen source at 85?°C under base-free condition. Good to the excellent yield of secondary alcohols, gram scale synthesis, and high TON and TOF made this catalytic system interesting.
Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
, p. 7652 - 7666 (2021/12/13)
Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
Palladium Complexes Bearing Chiral bis(NHC) Chelating Ligands on a Spiro Scaffold: Synthesis, Characterization, and Their Application in the Oxidative Kinetic Resolution of Secondary Alcohols
Zhang, Dao,Yu, Jueqin
, p. 605 - 613 (2020/02/13)
A series of chiral bis-N-heterocyclic carbene ligands H2[(S)-1a-d]X2 (X = Br, I) on a spiro scaffold and their palladium complexes (S)-2a-d and (S)-3a,b were prepared and applied in the enantioselective oxidative kinetic resolution of secondary alcohols. The corresponding alcohols can be obtained in high yields with moderate to excellent ee values.
