22426-24-0Relevant academic research and scientific papers
Practical access to (S)-heterocyclic aromatic acetates via CAL-B/Na2CO3-deacylation and Mitsunobu reaction protocol
Aribi-Zouioueche, Louisa,Bra?a, Nabila,Merabet-Khelassi, Mounia,Toffano, Martial
, (2022/02/11)
Herein, we report the preparation of enantiomerically pure forms of 2,3-dihydrobenzofuran-3-ol (1), chroman-4-ol (2), thiochroman-4-ol (3), 1-(furan-2-yl) ethanol (5) and 1-(thiophen-2-yl) ethanol (6), through a kinetic resolution catalysed by Candida antarctica lipase B/Na2CO3 hydrolysis sequence in organic media. The (R)-furnished alcohols and the (S)-remained acetates are recovered enantiopures (ee?>99%, E???200, Conv = 50%). Those ideal enzymatic kinetic resolution (EKRs) are well incorporated to the Mitsunobu inversion protocol in a one pot procedure to give (S)-heterocyclic acetates (1a–3a) in good to high enantiomeric excess (88%–92% ee). Whilst, the (S)-heteroaromatic acetates (5a and 6a) are given with moderate enantiomeric excess (51%–62% ee). All the (S)-acetates are given in good isolated chemical yields (>80%) allowing to overcome the maximum of 50% yield which could be usually reached in a regular kinetic resolution processes.
Tuning lipase-catalysed kinetic resolution of 2-substituted thiophenes and furans: A scalable chemoenzymatic route to masked γ-bis-oxo-alcohols
Ferreira, Dartagnan S.P.,Ferreira, Jeiely G.,Filho, Everaldo F.S.,Princival, Jefferson L.
, p. 37 - 45 (2016/02/18)
The demand for greener and applicable approaches aiming at the synthesis of optically active compounds as single enantiomers has seen a significant growth worldwide. Since most of the chemically synthesized compounds are produced as racemates their kinetic resolution has been of great interest. For this purpose a number of chemo-enzymatic approaches were proposed. One of such approaches, the use of isolated lipases, is a well-established alternative. Herein we report the kinetic resolutions of 2-Substituted five-membered heteroaromatic rings. By optimizing the reaction conditions it was possible to produce (2-hydroxy)-2-substituted furans and thiophenes in high enantiomeric ratio (E > 200). Thus, racemic mixtures of compounds with slight structural differences were resolved. The current chemo-enzymatic strategy has been applied to a scalable approach leading to the formation of the enantiopure (S)-2i a well-known building block used for the synthesis of bioactive natural compounds.
Entrapment of Pseudomonas cepacia lipase with peracetylated β-cyclodextrin in sol-gel: Application to the kinetic resolution of secondary alcohols
Ghanem, Ashraf,Schurig, Volker
, p. 2547 - 2555 (2007/10/03)
Co-lyophilized Pseudomonas cepacia lipase with peracetylated β-cyclodextrin was immobilized by the sol-gel process. The gel-entrapped lipase/cyclodextrin was prepared by the hydrolysis of methyltrimethoxysilane (MTMS) in the presence of the co-lyophilized lipase with peracetylated β-cyclodextrin prepared with different weight ratios (enzyme to CD). This type of enzyme preparation was subsequently used in the kinetic resolution of a set of secondary alcohols using isopropenyl acetate as an innocuous acyl donor in toluene as the organic medium. The resulting chiral alcohols (substrate) and the corresponding acetates (product) were baseline separated in one analysis without derivatization using gas chromatography on a new chiral stationary phase (CSP) Chirasil-β-Dex containing an undecamethylene spacer (C11-Chirasil-Dex).
Lipase-catalyzed Irreversible Transesterification of Secondary Alcohols Using Isopropenyl Acetate
Ghanem, Ashraf,Schurig, Volker
, p. 1151 - 1157 (2007/10/03)
Asymmetric acetylation of a set of secondary alcohols with the innocuous acyl donor isopropenyl acetate catalyzed by a lipase from Pseudomonas cepacia immobilized on ceramic particles (PSL-C) in toluene as organic medium afforded the chiral alcohols and the corresponding acetates in high enantiomeric excess (up to 99%). An effective baseline separation of the enantiomers of both substrate and product was performed in one analysis without derivatization using gas chromatography on a new chiral stationary phase (CSP) Chirasil-β-Dex containing an undecamethylene spacer (C11-Chirasil-Dex).
Chemoenzymic Synthesis of Chiral Furan Derivatives: Useful Building Blocks for Optically Active Structures
Drueckhammer, Dale G.,Barbas, Carlos F.,Nozaki, Kenji,Wong, Chi-Huey,Wood, Cynthia Y.,Ciufolini, Marco A.
, p. 1607 - 1611 (2007/10/02)
Practical procedures have been developed for the enantioselective reduction of 2-acetylfuran (6a) and 2-(trifluoroacetyl)furan (6b) to the corresponding carbinols (S)-1 and 7b with 88-90percent ee using Thermoanaerobium brockii alcohol dehydrogenase coupled with an NADPH regeneration system.Kinetic resolution of racemic (S)-1 via lipase-catalyzed esterification, followed by cholesterol esterase or lipase-catalyzed hydrolysis of the ester gives (R)-1 with 94percent ee.Conversion of (S)-1 to the dihydropyranones 4 and 5 without racemization has been illustrated.Enantioselectivehydrolysis of N-protected furylglycine methyl esters catalyzed by papain gave the unreacted esters and and the free acids (S form) both in 45percent yield and 97percent ee.The resolved furylglycines are excellent substrates for the synthesis of optically active synthons for alkaloids.
