104974-60-9Relevant articles and documents
Highly activity asymmetric hydrogenation of enones catalyzed by iridium complexes with chiral diamines and achiral phosphines
Chen, Hua,Gao, Xiuli,Jiang, Jian,Li, Chun,Li, Li,Lu, Xunhua,Wang, Mengna,Zhang, Lin,Zhang, Ling
, (2020)
A selective asymmetric hydrogenation of enones has been well established by using an iridium complex composed of cheap phosphine ligands and cinchona alkaloids derivatives as catalyst. A wide range of allylic alcohol products could be obtained in high chemoselectivities (up to 99.6%), enantioselectivities (70.1% ee) and high activities (up to 3.64 × 104(1/h) TOF). This catalytic system opens a new way of selective asymmetric hydrogenation and the method can be of practical value.
Production of enantiomerically enriched chiral carbinols using whole-cell biocatalyst
Bayda?, Yasemin,Kalay, Erbay,?ahin, Engin
, p. 29 - 37 (2022)
Biocatalytic asymmetric reduction of ketone is an efficient method for the production of chiral carbinols. The study indicates selective bioreduction of different ketones (1–8) to their respective (R)-alcohols (1a–8a) in low to high selectivity (0- >99%) with good yields (11–96%). In this work, whole-cell of Lactobacillus kefiri P2 catalysed enantioselective reduction of various prochiral ketones was investigated. (R)-4-Phenyl-2-butanol 2a, which is used as a precursor to antihypertensive agents and spasmolytics (anti-epileptic agents), was obtained using L kefiri P2 in 99% conversion and 91% enantiomeric excess (ee). Moreover, bioreduction of 2-methyl-1-phenylpropan-1-one substrate 8, containing a branched alkyl chain and difficult to asymmetric reduction with chemical catalysts as an enantioselective, to (R)-2-methyl-1-phenylpropan-1-ol (8a) in enantiomerically pure form was carried out in excellent yield (96%). The gram-scale production was carried out, and 9.70 g of (R)-2-methyl-1-phenylpropan-1-ol (8a) in enantiomerically pure form was obtained in 96% yield. Also especially, the yield and gram scale of (R)-2-methyl-1-phenylpropan-1-ol (8a) synthesised through catalytic asymmetric reduction using the biocatalyst was the highest report so far. The efficiency of L kefiri P2 for the conversion of the substrates and ee of products were markedly influenced by the steric factors of the substrates. This is a cheap, clean and eco-friendly process for production of chiral carbinols compared to chemical processes.
Asymmetric Transfer Hydrogenation of Ketones Using New Iron(II) (P-NH-N-P′) Catalysts: Changing the Steric and Electronic Properties at Phosphorus P′
Smith, Samantha A. M.,Prokopchuk, Demyan E.,Morris, Robert H.
, p. 1204 - 1215 (2017)
The asymmetric transfer hydrogenation (ATH) of ketones is an efficient method for producing enantio-enriched alcohols which are used as intermediates in a variety of industrial processes. Here we report the synthesis of new iron ATH precatalysts (S,S)-[FeBr(CO)(Ph2PCH2CH2NHCHPhCHPhNC=CHCH2PR′2)][BPh4] (R′=Et, and ortho-tolyl (o-Tol)) where one of the phosphine groups is modified with small alkyl and large aryl substituents to probe the effect of this change on the activity and selectivity of the catalytic system. A simple reversible equilibrium kinetic model is used to obtain the initial TOF and the inherent enantioselectivity S=kR/kS of these catalysts along with those for the previously reported catalysts with R′=Ph and Cy for the ATH of acetophenone. With an increase in the size of the PR′2 group, the TOF goes through a maximum at PPh2 while the S value goes through a maximum of 510 at R′=Cy. The complex with R′=o-Tol starts with a high S value of 200 but is rapidly changed to a second catalyst with an S value of 28. For the reduction of acetophenone to (R)-1-phenylethanol, turnover numbers of up to 5200 and ee up to 98 % were achieved. The chemotherapeutic pharmaceutical precursor (R)-(3′,5′-bis(trifluoromethyl))-1-phenylethanol is synthesized in up to 95 % ee. Several other alcohols can be prepared in greater than 90 % ee by choosing the precatalyst with the correctly matched steric properties. A hydride complex derived from the catalyst with R′=Cy is characterized by NMR spectroscopy. It is proposed that low concentration trans-hydride carbonyl complexes with the FeH parallel to the NH of the ligand are the active catalysts in all of these systems.
Green and Recyclable Medium for Asymmetric Hydrogenation of Benzalacetone Catalyzed by RuCl2(TPPTS)2-(S,S)-DPENDS
Qin, Ruixiang,Wang, Jinbo,Xiong, Wei,Feng, Jian,Liu, Derong,Chen, Hua
, p. 1146 - 1153 (2012)
PEG400-H2O was a green and recyclable reaction medium for asymmetric hydrogenation of benzalacetone catalyzed by ruthenium achiral monophosphine complex, RuCl2(TPPTS)2 (TPPTS: P(m-C6H4SO3Na)3), which was modified by (S,S)-DPENDS (disodium salt of sulfonated (S,S)-1,2-diphenyl-1,2-ethylene-diamine). Under the optimized conditions, the chemoselectivity for 4-phenyl-3-buten-2-ol was 98.5% with a corresponding ee value of 74.3%. The resulting products could easily be separated from the catalyst by extraction with n-hexane. The catalyst immobilized on PEG400-H2O could be recycled and reused at least five times without significant loss of chemoselectivity and enantioselectivity.
An unsymmetrical iron catalyst for the asymmetric transfer hydrogenation of ketones
Smith, Samantha A.M.,Morris, Robert H.
, p. 1775 - 1779 (2015)
A new iron(II)(Ph2P-NH-N-PCy2) complex with a dicyclohexylphosphino group trans to the NH group was found to catalyze the asymmetric transfer hydrogenation of a variety of ketones with high enantioselectivity.
Oxidation of aryl-substituted allylic alcohols by an optically active Fe(III)(porph*) catalyst: Enantioselectivity, diastereoselectivity and chemoselectivity in the epoxide versus enone formation
Adam, Waldemar,Prikhodovski, Serguei,Roschmann, Konrad J,Saha-Moeller, Chantu R
, p. 2677 - 2681 (2001)
A set of aryl-substituted allylic alcohols (±)-2 was oxidized using the chiral Fe(porph*) complex 1 as the catalyst and iodosyl benzene (PhIO) as the oxygen source. Whereas one enantiomer of the allylic alcohol 2 is preferentially epoxidized to give the threo- or cis-epoxy alcohol 3 (up to 43% e.e.) as the main product (d.r. up to >95:5), the other enantiomer of 2 is enriched (up to 31% e.e.). Some non-stereoselective allylic oxidation to give the enone 4 also takes place. The observed diastereo- and enantioselectivities in the epoxidation reactions are rationalized in terms of a synergistic interplay between the hydroxy-directing effect and the steric interactions of the catalyst 1 and the substrate 2.
Chelate ring size effects of Ir(P,N,N) complexes: Chemoselectivity switch in the asymmetric hydrogenation of α,β-unsaturated ketones
Bényei, Attila C.,Bakos, József,Császár, Zsófia,Farkas, Gergely,Szabó, Eszter Z.
, (2020/08/13)
A novel, highly modular approach has been developed for the synthesis of new chiral P,N,N ligands with the general formula Ph2P(CH3)CH(CH2)mCH(CH3)NHCH2CH2(CH2)nN(CH3)2 and Ph2P(CH3)CHCH2CH(CH3)NHCH2(CH2)n-2-Py (m, n = 0, 1). The systematic variation of their P–N and N–N backbone led to the conclusion that the activity, chemo- and enantioselectivity in the hydrogenation of α,β-unsaturated ketones are highly dependent on the combination of the two bridge lengths. It has been found that a minor change in the ligand's structure, i. e. varying the value of m from 1 to 0, can switch the chemoselectivity of the reaction, from 80percent C[dbnd]O to 97percent C[dbnd]C selectivity.
