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Hapu D.,University of Medicine and Pharmacy, Cluj-Napoca | Brem J.,Babe Bolyai University of Cluj Napoca | Zaharia V.,University of Medicine and Pharmacy, Cluj-Napoca
Tetrahedron Asymmetry | Year: 2011

The lipase mediated selective O-acylation and alcoholysis of the corresponding alcohols/butanoates have been investigated for the production of both (R)- and (S)-1-(2-aryl-thiazol-5-yl)ethanols. In terms of stereoselectivity and activity, CaL-B mediated selective acylation gave similar good results (c = 50%, E 200) in comparison with CaL-A mediated alcoholysis (c = 50%, E 200). Using the sequential kinetic resolution: first a CaL-B catalyzed (R)-selective O-acylation of racemic alcohols rac-2a-d followed by a CaL-A mediated methanolysis of the previously obtained enantiomerically enriched (R)-butanoates (R)-3a-d yielded (with 39-46% yields) both enantiopure forms of the 1-(2-aryl-thiazol-5-yl)ethanols. © 2011 Elsevier Ltd. All rights reserved.


Brem J.,Babe Bolyai University of Cluj Napoca | Naghi M.,Babe Bolyai University of Cluj Napoca | Toa M.-I.,Babe Bolyai University of Cluj Napoca | Boros Z.,Budapest University of Technology and Economics | And 3 more authors.
Tetrahedron Asymmetry | Year: 2011

The lipase-catalyzed kinetic resolution of a series of aromatic β-hydroxy esters in organic media has been investigated. Decanoic acid and its esters were successfully used as acyl donors for selective O-acylation. The regio- and enantioselective enzymatic hydrolysis of the decanoate moiety of the diesters was also investigated. The effects of water, reaction temperature, and solvent type, and also the influence of substrates structure on the catalytic behavior of potential commercially available lipases were studied. A novel procedure was developed for the efficient and highly stereoselective synthesis of both enantiomers of both novel and known target compounds. Copyright © 2011 Published by Elsevier Ltd. All rights reserved.


Brem J.,Babe Bolyai University of Cluj Napoca | Brem J.,University of Turku | Turcu M.C.,University of Turku | Paizs C.,Babe Bolyai University of Cluj Napoca | And 4 more authors.
Process Biochemistry | Year: 2012

Lipase AK "Amano" 20 from Pseudomonas fluorescens (PFL) was immobilized using diverse immobilization techniques. The methods developed, especially the optimized sol-gel procedure, enabled the fine tuning of enzymatic activity and enantioselectivity for the kinetic resolution of racemic ethyl 3-aryl-3-hydroxypropanoates. The aryl moieties of the racemates include furan-2 and 3-yl, thiophen-2 and 3-yl, benzofuran-2-yl, benzo[b]thiophen-2-yl, as well as phenyl and 4-chloro- and 4-methoxyphenyl groups. The optimized PFL sol-gel preparation (encapsulation from the aqueous solution of PFL, sucrose and Celite in situ) was shown to be efficiently reusable in ten cycles and highly enantioselective with E > 200 to all other substrates except furan-2 and 3-yl and thiophen-2 and 3-yl substituted compounds with E 108-184. © 2011 Elsevier Ltd. All rights reserved.


Brem J.,Babe Bolyai University of Cluj Napoca | Pilbak S.,Budapest University of Technology and Economics | Paizs C.,Babe Bolyai University of Cluj Napoca | Banoczi G.,Budapest University of Technology and Economics | And 3 more authors.
Tetrahedron Asymmetry | Year: 2011

The synthesis of both enantiomers of 1-(10-ethyl-10H-phenothiazin-1,2, and 4-yl)ethanols 1a-c and their acetates via enantioselective methanolysis of the corresponding racemic esters rac 2a-c with lipase B from Candida antarctica (CaL-B) or/and by acylation of the racemic alcohols with the lipase A or lipase B from C. antarctica (CaL-A and CaL-B) is described. The absolute configuration of enantiopure 1-(10-ethyl-10H-phenothiazin-1-yl)ethyl acetate 2a was assigned as (R) by using QM/MM(hf/3-21g:uff) calculations within the CaL-B (1LBT crystal structure) enzymic environment. © 2011 Elsevier Ltd. All rights reserved.


Brem J.,University of Turku | Brem J.,Babe Bolyai University of Cluj Napoca | Liljeblad A.,University of Turku | Paizs C.,Babe Bolyai University of Cluj Napoca | And 3 more authors.
Tetrahedron Asymmetry | Year: 2011

The preparative scale kinetic resolution of racemic ethyl 2- and 3-furyl- and 2- and 3-thienyl-3-hydroxypropanoates has been performed by Candida antarctica lipases A and B with vinyl esters. A study based on the present work together with the literature has been carried out in terms of lipase enantiopreference and substrate structure. We also discuss the excellent behavior of the lipase A in O-acylations of secondary alcohols with respect to enantiopreference. © 2011 Elsevier Ltd. All rights reserved.

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