52780-12-8Relevant academic research and scientific papers
Enantioselective potential of polysaccharide-based chiral stationary phases in supercritical fluid chromatography
Kucerova, Gabriela,Kalikova, Kveta,Tesarova, Eva
supporting information, p. 239 - 246 (2017/05/29)
The enantioselective potential of two polysaccharide-based chiral stationary phases for analysis of chiral structurally diverse biologically active compounds was evaluated in supercritical fluid chromatography using a set of 52 analytes. The chiral selectors immobilized on 2.5?μm silica particles were tris-(3,5-dimethylphenylcarmabate) derivatives of cellulose or amylose. The influence of the polysaccharide backbone, different organic modifiers, and different mobile phase additives on retention and enantioseparation was monitored. Conditions for fast baseline enantioseparation were found for the majority of the compounds. The success rate of baseline and partial enantioseparation with cellulose-based chiral stationary phase was 51.9% and 15.4%, respectively. Using amylose-based chiral stationary phase we obtained 76.9% of baseline enantioseparations and 9.6% of partial enantioseparations of the tested compounds. The best results on cellulose-based chiral stationary phase were achieved particularly with propane-2-ol and a mixture of isopropylamine and trifluoroacetic acid as organic modifier and additive to CO2, respectively. Methanol and basic additive isopropylamine were preferred on amylose-based chiral stationary phase. The complementary enantioselectivity of the cellulose- and amylose-based chiral stationary phases allows separation of the majority of the tested structurally different compounds. Separation systems were found to be directly applicable for analyses of biologically active compounds of interest.
(R)- and (S)-3-Hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone, New Chiral Auxiliaries for the Asymmetric Synthesis of α-Arylpropanoic Acids.
Camps, Pelayo,Gimenez, Silvia
, p. 991 - 1000 (2007/10/03)
Reaction of rac-α-arylpropanoyl chlorides with (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone (R)- and (S)-1, in the presence of triethylamine, under standard esterification conditions, gave (R,R)- and (S,S)-3, respectively, with high diastereoselectivity.Controlled acidic hydrolysis afforded the corresponding (R)- or (S)-α-arylpropanoic acids with high enantioselectivity, the chiral auxiliary being recovered efficiently.
1,1′-binaphthalene-2,2′-diol as a chiral auxiliary. Diastereoselective alkylation of binaphthyl esters, complex-induced proximity effects in enolate formation, and one-step synthesis of an optically active β-substituted ketone
Tanaka, Fujie,Node, Manabu,Tanaka, Kiyoshi,Mizuchi, Maki,Hosoi, Shinzo,Nakayama, Masayo,Taga, Tooru,Fuji, Kaoru
, p. 12159 - 12171 (2007/10/03)
Diastereoselective alkylation of enolates derived from (S)-naphthyl phenylacetate 1 with LDA in THF gave the S,S-isomer as a major product. The diastereoselectivity increased as the bulkiness of the alkylating agent was increased. The low diastereomeric excess (~70%) of methylation was markedly raised to 92% by the use of n-BuLi as a base due to the complex-induced proximity effect (CIPE) in enolate formation. This highly diastereoselective methylation was used to synthesize the clinically important anti-inflammatory drugs (S)-naproxen (60) and (S)-suprofen (68). The stereochemistry of ketene trimethylsilyl acetals generated from several phenylacetates was investigated to understand the origin of the diastereoselectivity in this alkylation. Methyl phenylacetate (46) predominantly gave a (Z)-enolate by kinetic deprotonation, while the (E)-enolate was predominantly obtained from phenyl phenylacetate (47). An optically active ketone (88) was synthesized from binaphthyl ester 84 by a one-pot procedure involving the 1,4-addition, followed by the 1,2-addition, of organometallics. The CIPE again played a crucial role in the high enantiomeric excess in this case.
Complex-induced proximity effects in enolate formation. Highly diastereoselective α-methylation of binaphthyl esters of arylacetic acids
Fuji,Node,Tanaka
, p. 6553 - 6556 (2007/10/02)
Highly diastereoselective methylation of binaphthyl esters of arylacetic acids and its application to the syntheses of antiinflammatory drugs, (S)-suprofen and (S)-naproxen.
Enhancing the enantioselectivity of Candida lipase catalyzed ester hydrolysis via noncovalent enzyme modification
Wu, Shih-Hsiung,Guo, Zhi-Wei,Sih, Charles J.
, p. 1990 - 1995 (2007/10/02)
When the lipase of Candida cylindracea was treated with deoxycholate and organic solvents (ether-ethanol, 1:1), the enzyme apparently unfolded and refolded to generate a more stable conformer, termed lipase A-form. This lipase A-form was found to be considerably more enantioselective than the native enzyme toward the hydrolysis of a variety of (±)-arylpropionic and (±)-phenoxypropionic esters.
