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1.
Anna Brodzka Dominik Koszelewski Malgorzata Cwiklak Ryszard Ostaszewski 《Tetrahedron: Asymmetry》2013,24(8):427-433
A new chemoenzymatic method for the synthesis of enantiomerically pure 3-phenyl-γ-aminobutyric acid 1 and 4-phenyl-pyrrolid-2-one 9 based on the enzymatic kinetic resolution of 3-phenyl-4-pentenoic acid 2 is described herein. Enzymatic resolution of the racemic substrate provided products with good enantioselectivity upon esterification. In these reactions, a new class of alkoxy group donor—orthoesters, acetals and ketals were used. The best results of the enzymatic kinetic resolution were obtained for triethyl orthoacetate in toluene solvent. 相似文献
2.
Enzymatic kinetic resolution of piperidine atropisomers: synthesis of a key intermediate of the farnesyl protein transferase inhibitor, SCH66336 总被引:1,自引:0,他引:1
Morgan B Zaks A Dodds DR Liu J Jain R Megati S Njoroge FG Girijavallabhan VM 《The Journal of organic chemistry》2000,65(18):5451-5459
The resolution of secondary amines via enzyme-catalyzed acylation is a relatively rare process. The kinetic resolution of a series of intermediates of SCH66336 (1), by either enzymatic acylation of the pendant piperidine (4, 5) or hydrolysis of the corresponding carbamate 3, was investigated. In the case of 4, the molecule exists as a pair of enantiomers due to atropisomerism about the exocyclic double bond. The enzymatic acylation of (+/-)-4 was optimized in terms of acylating agent, solvent, and moisture content. The use of lipase, Toyobo LIP-300, and trifluoroethyl isobutyrate as acylating agent resulted in isobutyrylation of the (+)-enantiomer, which is easily separated from the unwanted (-)-4. Hydrolysis of the isobutyramide 6c yielded the desired (+)-4 in high enantiomeric excess. (-)-4 may be recovered from the resolution step, racemized, and resubjected to enzymatic acylation to increase material throughput. 相似文献
3.
《Tetrahedron: Asymmetry》2001,12(16):2283-2287
Both enantiomers of 4-acetoxy- and 4-hydroxytetralone have been obtained with high enantiomeric purity by kinetic resolution using enzymes. 3-Hydroxyindanone was successfully resolved using enzymatic transesterification. The absolute configuration of the products were established by literature precedence. 相似文献
4.
Waldemar Adam Chantu R. Saha-M?ller Oliver Weichold 《Monatshefte für Chemie / Chemical Monthly》2000,13(7):697-705
Optically active diastereomeric β-hydroperoxy esters 4 have been prepared by singlet oxygen ene reaction of β,γ-unsaturated esters 3 and subsequent horseradish peroxidase (HRP) catalyzed kinetic resolution of the ene product. The highest enantiomeric excess (up to 95%) has been obtained for the isopropyl ester threo-4c, which establishes that the size of the remote ester functionality exercises appreciable control in the enantioselectivity of the enzymatic kinetic resolution. 相似文献
5.
Dominik Koszelewski Malgorzata Cwiklak Ryszard Ostaszewski 《Tetrahedron: Asymmetry》2012,23(17):1256-1261
A new chemoenzymatic method is proposed for the synthesis of enantiomerically pure 4-phenyl-1,4-dihydro-2H-isoquinolines based on the enzymatic kinetic resolution of 2-acetyl-4-phenyl-1,4-dihydro-2H-isoquinolin-3-one. For the enzymatic resolution of the racemic substrate, readily available ‘home made’ animal liver acetone powders (LAPs) were used. Excellent enantioselectivity, exceeding 500, was achieved in a short reaction time upon application of turkey liver acetone powder as the biocatalyst. Reduction of obtained product led to the formation of amine (R)-1, which is hardly available using standard procedures. These results show that N-acetyl lactams are a new type of substrate for enzymatic biotransformations. 相似文献
6.
Epoxy quinol 1a was prepared on a multi-gram scale by Noyori transfer hydrogenative desymmetrization of the readily available meso epoxy diketone 4. Although the intrinsic enantioselectivity for the desymmetrization was modest (82:18 er at 4% conversion), a highly enantiopure product (99.6:0.4 er) could be obtained in one operation in 44% yield via kinetic resolution of the minor enantiomer with long reaction times (48 h), or in 73% yield by combination with an enzymatic resolution of a 93:7 er mixture. 相似文献
7.
Wuyts S De Temmerman K De Vos D Jacobs P 《Chemical communications (Cambridge, England)》2003,(15):1928-1929
Acid zeolites like H-Beta are efficient heterogeneous catalysts for racemization of benzylic alcohols in water; by combination of the racemization with an enzymatic kinetic resolution in a two-phase system, enantiomerically pure esters were obtained in high yield via a dynamic kinetic resolution. 相似文献
8.
László Csaba Bencze Csaba Paizs Monica Ioana Toşa Maria Trif Florin Dan Irimie 《Tetrahedron: Asymmetry》2010,21(16):1999-2004
A highly stereoselective enzymatic kinetic resolution of novel various substituted racemic furylbenzthiazole-2-yl-ethanols and their acetates has been developed. Both processes, the enzymatic acylation of the racemic alcohols and the enzymatic methanolysis of racemic acetates yielded highly enantiomerically enriched (ee >98%) resolution product, when CaL-B was used as a biocatalyst in acetonitrile. The absolute configuration of the obtained (R)-(+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol was determined by a detailed 1H NMR study of rac- and (+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol Mosher derivatives. 相似文献
9.
Waldemar Adam Chantu R. Saha-Möller Oliver Weichold 《Monatshefte für Chemie / Chemical Monthly》2000,131(6):697-705
Summary. Optically active diastereomeric β-hydroperoxy esters 4 have been prepared by singlet oxygen ene reaction of β,γ-unsaturated esters 3 and subsequent horseradish peroxidase (HRP) catalyzed kinetic resolution of the ene product. The highest enantiomeric excess
(up to 95%) has been obtained for the isopropyl ester threo-4c, which establishes that the size of the remote ester functionality exercises appreciable control in the enantioselectivity
of the enzymatic kinetic resolution.
Received December 20, 1999. Accepted (revised) February 11, 2000 相似文献
10.
《Tetrahedron: Asymmetry》2006,17(15):2252-2259
The enzymatic resolution of racemic mixtures of hydroxy tellurides with a range of lipases has been investigated. Lipase-B from Candida antarctica (CALB) gave the best conversions, providing both enantiomers with high enantiomeric purity. A comparative study of the effect of solvent and substrate on the enzymatic kinetic resolution was performed. 相似文献
11.
Substituted propargylic esters, resistant to complete ethylene cross-metathesis at ambient pressure, underwent cross-metathesis with ethylene at elevated pressure (4 atm) to give 2-substituted butadienes in good to excellent yields. Enantioenriched propargylic acetates, obtained through enzymatic kinetic resolution of secondary propargyl alcohols, similarly underwent ethylene metathesis with retention of stereochemistry at the chiral center. 相似文献
12.
13.
(S)-selective kinetic resolution and chemoenzymatic dynamic kinetic resolution of secondary alcohols
Borén L Martín-Matute B Xu Y Córdova A Bäckvall JE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,12(1):225-232
(S)-Selective kinetic resolution was achieved through the use of a commercially available protease, which was activated with a combination of two different surfactants. The kinetic resolution (KR) process was optimized with respect to activation of the protease and to the acyl donor. The KR proved to be compatible with a range of functionalized sec-alcohols, giving good to high enantiomeric ratio values (up to >200). The enzymatic resolution was combined with a ruthenium-catalyzed racemization to give an (S)-selective dynamic kinetic resolution (DKR) of sec-alcohols. The DKR process works under very mild reaction conditions to give the corresponding esters in high yields and with excellent enantioselectivities. 相似文献
14.
15.
[reaction: see text] An efficient kinetic resolution of racemic gamma-hydroxy amides 1 was performed via Pseudomas cepacia lipase (PS-C)-catalyzed transesterification. The enzyme PS-C tolerates both variation in the chain length and different functionalities giving good to high enantioselectivity (E values of up to >250). The combination of enzymatic kinetic resolution with a ruthenium-catalyzed racemization led to a dynamic kinetic resolution. The use of 2,4-dimethyl-3-pentanol as a hydrogen source to suppress ketone formation in the dynamic kinetic resolution yields the corresponding acetates in good yield and good to high enantioselectivity (ee's up to 98%). The synthetic utility of this procedure was illustrated by the practical synthesis of the versatile intermediate gamma-lactone (R)-5-methyltetrahydrofuran-2-one. 相似文献
16.
Dominik Koszelewski Daniel Paprocki Anna Brodzka Ryszard Ostaszewski 《Tetrahedron: Asymmetry》2017,28(6):809-818
A novel synthetic route to optically active saturated and unsaturated δ-lactones based on enzymatic kinetic resolution and ring-closing metathesis reactions has been proposed. The influence of temperature, co-solvent, organic additives and the substrate structure on the catalytic behavior of selected hydrolases was studied. The substantial impact of the organic co-solvent and surfactant type on the enzymatic activity and enantioselectivity was observed providing enantiomerically pure δ-hydroxy-α,β-unsaturated esters. The established protocol combining enzymatic kinetic resolution with ring closing metathesis was successfully applied in the synthesis of the enantiomerically pure (6R)-phenyl-5,6-dihydro-2H-pyran-2-one which plays crucial role in the synthesis of the number of bioactive compounds. 相似文献
17.
An enzymatic approach has been successfully utilized in the total synthesis of (–)‐malyngolide and its C(5)‐epimer. The required configuration was established by an enzymatic kinetic resolution and Sharpless asymmetric dihydroxylation. 相似文献
18.
《Tetrahedron letters》2003,44(40):7411-7415
The first total synthesis of two E type I phytoprostanes from furan, azelaic acid monomethyl ester and rac-1,2-epoxybutane is described. The key features of our synthetic strategy encompass an enzymatic kinetic resolution of a hydroxycyclopentenone, a Co-salen hydrolytic kinetic resolution of a terminal epoxide and a tandem conjugate addition/diastereoselective protonation sequence to construct the protected phytoprostanes. Mild cleavage of the silyl protective groups followed by enzymatic ester hydrolysis afforded the free E-type phytoprostanes. 相似文献
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20.
The consumption of amphetamine is illicit and controlled due to both the elicited behavioural deviations and the toxicity effects reported in abusers. Thus, amphetamine levels in biological samples must be monitored in several clinical and forensic circumstances. In spite of the interspecies differences in the preferred route of biotransformation, benzylmethylketone, benzoic acid and 4-hydroxyamphetamine are the principal metabolites of amphetamine. However, the clinical and forensic studies are focused in the parent compound and in 4-hydroxyamphetamine since benzylmethylketone is a minor metabolite in human and benzoic acid is also an endogenous compound. In the present study amphetamine and its metabolite, 4-hydroxyamphetamine, are quantified in urine by HPLC after derivatization with 4-dimethylaminoazobenzene-4'-sulfonyl chloride (dabsyl chloride). This derivatization procedure transforms amphetamine and its hydroxylated metabolite in compounds with similar lipofilicity, enabling their quantitative and simultaneous extraction with an organic solvent. The precision of the HPLC technique was 7.3 and 10.0% for amphetamine and 4-hydroxyamphetamine derivatives, respectively. For the overall procedure, including enzymatic hydrolysis, derivatization and extraction of the derivatives, the obtained values were 9.3 and 6.2%. Recoveries obtained from spiked urines for amphetamine and 4-hydroxyamphetamine were better than 97% and 94% (mean value), respectively. The detection limits of the method was 10 ng for both compounds. The principal advantages of the present proposed method are the stability of the dabsyl derivatives at room temperature and the detection carried out in the visible region, reducing the interferences detected. 相似文献