- Acylative Kinetic Resolution of Alcohols Using a Recyclable Polymer-Supported Isothiourea Catalyst in Batch and Flow
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A polystyrene-supported isothiourea catalyst, based on the homogeneous catalyst HyperBTM, has been prepared and used for the acylative kinetic resolution of secondary alcohols. A wide range of alcohols, including benzylic, allylic, and propargylic alcohols, cycloalkanol derivatives, and a 1,2-diol, has been resolved using either propionic or isobutyric anhydride with good to excellent selectivity factors obtained (28 examples, s values up to 600). The catalyst can be recovered and reused by a simple filtration and washing sequence, with no special precautions needed. The recyclability of the catalyst was demonstrated (15 cycles) with no significant loss in either activity or selectivity. The recyclable catalyst was also used for the sequential resolution of 10 different alcohols using different anhydrides with no cross-contamination between cycles. Finally, successful application in a continuous flow process demonstrated the first example of an immobilized Lewis base catalyst used for the kinetic resolution of alcohols in flow.
- Neyyappadath, Rifahath Mon,Chisholm, Ross,Greenhalgh, Mark D.,Rodríguez-Escrich, Carles,Pericàs, Miquel A.,H?hner, Georg,Smith, Andrew D.
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p. 1067 - 1075
(2018/02/14)
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- Kinetic resolution of secondary alcohols using amidine-based catalysts
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Kinetic resolution of racemic alcohols has been traditionally achieved via enzymatic enantioselective esterification and ester hydrolysis. However, there has long been considerable interest in devising nonenzymatic alternative methods for this transformation. Amidine-based catalysts (ABCs), a new class of enantioselective acyl transfer catalysts developed in our group, have demonstrated, inter alia, high efficacy in the kinetic resolution of benzylic, allylic, and propargylic secondary alcohols and 2-substituted cycloalkanols, and thus provide a viable alternative to enzymes.
- Li, Ximin,Jiang, Hui,Uffman, Eric W.,Guo, Lei,Zhang, Yuhua,Yang, Xing,Birman, Vladimir B.
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experimental part
p. 1722 - 1737
(2012/04/04)
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- Homobenzotetramisole: An effective catalyst for kinetic resolution of aryl-cycloalkanols
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Homobenzotetramisole (HBTM), a ring-expanded analogue of the previously reported catalyst BTM, displays higher catalytic activity and a different structure-selectivity profile. It displays good enantioselectivities in kinetic resolution of secondary benzylic alcohols but is particularly effective for 2-aryl-substituted cycloalkanols.
- Birman, Vladimir B.,Li, Ximin
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supporting information; experimental part
p. 1115 - 1118
(2009/04/07)
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- Kinetic and chemical resolution of different 1-phenyl-2-propanol derivatives
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Seven chiral target molecules containing a hydroxy group have been resolved by both biocatalytic and chemical means. The lipase-catalyzed acylation mainly yielded the acylated derivative of the (R)-alcohols with moderate enantiomeric excess and the enantiopure (S)-alcohols. In the course of the chemical resolution, first the dicarboxylic acid monoesters of the target molecules were synthesized and the resolution of these monoesters was attempted by different homochiral bases. By re-resolution and/or optimization of the reaction time and/or recrystallization, respectively, each molecule was produced in very high enantiomeric purity.
- Kiss, Violetta,Egri, Gabriella,Balint, Jozsef,Ling, Istvan,Barkoczi, Jozsef,Fogassy, Elemer
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p. 2220 - 2234
(2007/10/03)
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- Activity enhancement of pig liver esterase in organic solvents by colyophilization with methoxypolyethylene glycol: Kinetic resolution of alcohols
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Colyophilization of pig liver esterase with methoxypolyethylene glycol gave a catalyst, PLE/MPEG, which showed an enhanced activity in organic solvents. The PLE/MPEG catalyzed transesterification of the alcohols rac-1a- d with vinyl propionate in toluene proceeded with good to high selectivities. The addition of up to 1% of water to the reaction mixture resulted in a significant increase in enantioselectivity. Immobilization of PLE/MPEG for the batch-wise resolution was accomplished by its spontaneous adsorption on an ultrafiltration membrane.
- Ruppert, Stephan,Gais, Hans-Joachim
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p. 3657 - 3664
(2007/10/03)
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- Enantiomeric Resolution of 1-Phenyl-2-propanol by Pseudomonas cepacia
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Pseudomonas cepacia hydrolyzed rac-1-phenyl-2-propyl acetate and propionate asymmetrically, affording R(-)-1-phenyl-2-propanol and the ester of S(+)-1-phenyl-2-propanol.
- Horiuchi, Kenichi,Kobashi, Kazunori,Nagata, Hidetomo,Satoh, Toshinobu,Suemitsu, Rikisaku
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p. 1330 - 1331
(2007/10/02)
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- Anhydrides as Acylating Agents in Lipase-Catalyzed Stereoselective Esterification of Racemic Alcohols
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A new enzymatic method for the resolution of optically active alcohols from racemates is reported.It involves lipase-catalyzed esterification in organic solvents, with acetic, propionic, or butyric anhydrides as acylating agents.Lipase Amano P, from Pseudomonas fluorescens, adsorbed on Celite 577, was employed as stereoselective catalyst.Under these reaction conditions, the enzyme is not chemically modified by the anhydrides.A number of primary and secondary alcohols have been obtained in high optical purity by this procedure.
- Bianchi, Daniele,Cesti, Pietro,Battistel, Ezio
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p. 5531 - 5534
(2007/10/02)
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