76946-09-3Relevant articles and documents
Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
, (2022/01/04)
Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
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.
Production of enantiomerically enriched chiral carbinols using whole-cell biocatalyst
?ahin, Engin,Bayda?, Yasemin,Kalay, Erbay
, (2020/10/26)
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.
