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The solvent versatility of Chiralpak IB, a 3,5‐dimethylphenylcarbamate derivative of cellulose‐based chiral stationary phase, is demonstrated in the direct enantioselective HPLC monitoring of lipase‐catalyzed kinetic resolution of flurbiprofen in nonstandard HPLC organic solvents. Nonstandard HPLC organic solvents were used as the reaction media for the lipase‐catalysis and in mean time as diluent...
The distinctive nucleus of kainoid amino acids, (2S,3R)‐(+)‐2‐carboxypyrrolidine‐3‐acetic acid 6, was synthesized by a chemoenzymatic process, exploiting the diastereomeric cis/trans methyl pyroglutamate derivatives 10a, 10b, 10c/11a, 11b, 11c as key intermediates. These mixtures, when subjected to a kinetic resolution mediated by α‐chymotrypsin, reacted diastereo‐, regio‐, and enantioselectively...
S‐1‐(2‐Furyl) ethanol serves as an important chiral building block for the preparation of various natural products, fine chemicals, and is widely used in the chemical and pharmaceutical industries. In this work, lipase‐catalyzed kinetic resolution of (R/S)‐1‐(2‐furyl) ethanol using different acyl donors was investigated. Vinyl esters are good acyl donors vis‐à‐vis alkyl esters for kinetic resolution...
A series of representative optically active derivatives of 4‐hydroxy‐5‐alkylcyclopent‐2‐en‐1‐one were prepared from the respective 2‐furyl methyl carbinols via the Piancatelli rearrangement followed by the enzymatic kinetic resolution of racemates. Applicability of chiroptical methods (experimental and calculated electronic circular dichroism [ECD] and vibrational circular dichroism [VCD] spectra)...
Profens (2‐arylpropionic acids) are known as one of the major nonsteroidal antiinflammatory drugs (NSAIDs) used in the treatment of inflammation associated with tissue injury. The inflammatory activity of profens is mainly due to their (S)‐enantiomer, whereas they are commercially available not only as pure enantiomers, but as racemates as well. There are several methods widely used in order to obtain...
Compounds based on the pyrroloquinoxaline system can interact with serotonin 5‐HT3, cannabinoid CB1, and μ‐opioid receptors. Herein, a chiral pool synthesis of diastereomerically and enantiomerically pure bromolactam (S,R,R,R)‐14A is presented. Introduction of the cyclohexenyl ring at the N‐atom of (S)‐proline derivatives 8 or methyl (S)‐pyroglutamate (12) led to the N‐cyclohexenyl substituted pyrrolidine...
The lipase‐catalyzed enantioselectivehydrolysis of acetates containing tetrazole moiety was studied. Among all tested lipases, Novozyme SP 435 allowed to obtain optically active 4‐(5‐aryl‐2H‐tetrazol‐2yl)butan‐2‐ol and 1‐(5‐aryl‐2H‐tetrazol‐2yl)‐propan‐2‐ol and their acetates with the highest optical purities (ee = 95%‐99%) and excellent enantioselectivity (E>100). Some of the synthesized tetrazole...
A series of new N‐substituted benzimidazole derivatives was synthesized and their antifungal activity against Candida albicans was evaluated. The chemical step included synthesis of appropriate ketones containing benzimidazole ring, reduction of ketones to the racemic alcohols, and acetylation of alcohols to the esters. All benzimidazole derivatives were obtained with satisfactory yields and in relatively...
As the (R)‐enantiomer of racemic atenolol has no β‐blocking activity and no lack of side effects, switching from the racemate to the (S)‐atenolol is more favorable. Transesterification of racemic atenolol using free enzymes investigated as a resource to resolve the racemate via this method is limited. Screenings of enzyme, medium, and acetyl donor were conducted first to give Pseudomonas fluorescens...
The synthesis of (R)‐1‐(pyridin‐4‐yl)ethyl acetate was achieved over tandem palladium‐lipase catalyst with 100% selectivity using 4‐acetyl pyridine as a reactant. The 2% w/w palladium and lipase catalyst was successfully co‐immobilized in the microenvironment of the mesocellular foam and characterized by various techniques. The palladium metal from catalyst hydrogenated 4‐acetyl pyridine to form 1‐(pyridin‐4‐yl)ethanol...
Kinetic resolution of (R,S)‐atenolol is a faster strategy to produce (S)‐atenolol. Since this racemate is a less soluble compound, resolution of its ester offers high concentrations in the process. A good analytical method is required to observe the enantiomer concentrations. This paper described application of ultra‐fast liquid chromatography on the atenolol ester separation using different resolution...
The two enantiomers of ethyl 3‐hydroxybutyrate are important intermediates for the synthesis of a great variety of valuable chiral drugs. The preparation of chiral drug intermediates through kinetic resolution reactions catalyzed by esterases/lipases has been demonstrated to be an efficient and environmentally friendly method. We previously functionally characterized microbial esterase PHE21 and used...
We previously identified and characterized 1 novel deep‐sea microbial esterase PHE21 and used PHE21 as a green biocatalyst to generate chiral ethyl (S)‐3‐hydroxybutyrate, 1 key chiral chemical, with high enantiomeric excess and yield through kinetic resolution. Herein, we further explored the potential of esterase PHE21 in the enantioselective preparation of secondary butanol, which was hard to be...
Lipase‐catalysed enantioselective acetylation and deacetylation routes were investigated to prepare 1,5,6‐trisubstituted 7‐oxabicyclo[2.2.1]hept‐2‐ene skeleton in enantio‐pure form. The racemic alcohol (6) used in acetylation reaction was accessed through Diels‐Alder reaction of TBDMS‐protected furfuryl alcohol with maleic anhydride, followed by reduction‐benzylation‐desilylation sequence. After systematic...
Candida antarctica (CAL‐B) lipase‐catalyzed resolution of 1,3‐dialkyl‐3‐hydroxymethyl oxindoles has been performed to obtain (R)‐1,3‐dialkyl‐3‐acetoxymethyl oxindoles with up to 99% ee and (S)‐1,3‐dialkyl‐3‐hydroxymethyl oxindoles with up to 78% ee using vinyl acetate as acylating agent and acetonitrile as solvent transforming (S)‐3‐allyl‐3‐hydroxymethyl oxindole to (3S)‐1′‐benzyl‐5‐(iodomethyl)‐4,5‐dihydro‐2...
The racemization mechanism of tert‐butylphenylphosphido‐borane is investigated experimentally and theoretically. Based on this converging approach, it is shown, first, that several phosphido‐borane molecular species coexist at the time of the reaction and, second, that one particular of both initially assumed reactive routes most significantly contribute to the overall racemization process. From our...
An efficient lipase‐catalyzed stereoselective transesterification reaction system was established for resolution of 1‐(4‐methoxyphenyl)ethanol (MOPE) enantiomers. A series of lipases were tested and compared. The immobilized lipase Novozym 40086 is selected as the best choice. The effects of organic solvent, acyl donor, time and temperature on substrate conversion (c), and optical purity of the remaining...
Parasitic diseases, including malaria, leishmaniasis, and trypanosomiasis, affect billions of people and are responsible for almost 500,000 deaths/year. In particular, leishmaniasis, a neglected tropical disease, is considered a global public health problem because current drugs have several drawbacks including to toxicity, high cost, and drug resistance, which result in a lack of effective and readily...
In nature, flavin‐dependent halogenases (FDHs) catalyze site‐selective chlorination and bromination of aromatic natural products. This ability has led to extensive efforts to engineer FDHs for selective chlorination, bromination, and iodination of electron rich aromatic compounds. On the other hand, FDHs are unique among halogenases and haloperoxidases that exhibit catalyst‐controlled site selectivity...
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