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| 2. |
- Bogár, Krisztián, et al.
(författare)
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Chemoenzymatic Dynamic Kinetic Resolution of Allylic Alcohols : A Highly Enantioselective Route to Acyloin Acetates
- 2007
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 9:17, s. 3401-3404
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic kinetic resolution (DKR) of a series of sterically hindered allylic alcohols has been conducted with Candida antarctica lipase B (CALB) and ruthenium catalyst 1. The optically pure allylic acetates obtained were subjected to oxidative cleavage to give the corresponding acylated acyloins in high yields without loss of chiral information.
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| 3. |
- Bogár, Krisztián, et al.
(författare)
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Heterogenized Wilkinson's Catalyst for Transfer Hydrogenation of Carbonyl Compounds
- 2011
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Ingår i: European Journal of Organic Chemistry. - : Wiley-VCH Verlag GmbH 3690 & Co. KGaA, Weinheim. - 1434-193X .- 1099-0690. ; :23, s. 4409-4414
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Tidskriftsartikel (refereegranskat)abstract
- Wilkinson’s catalyst [RhCl(PPh3)3] was heterogenized on common silica by the use of a grafting/anchoring technique. The immobilized catalyst showed high activity and selectivity in transfer hydrogenation reactions of a range of carbonyl compounds in 2-propanol. Reactions carried out in 2-propanol at reflux afforded the corresponding alcohols in high yields in short reaction times. The heterogeneous feature ofthe catalyst allows for easy recovery and efficient reuse in the same reaction up to 5 times without any detectible loss of catalytic activity.
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| 4. |
- Bogár, Krisztián, et al.
(författare)
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High-yielding metalloenzymatic dynamic kinetic resolution of fluorinated aryl alcohols
- 2007
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Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 48:31, s. 5471-5474
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic kinetic resolution (DKR) of various fluorinated aryl alcohols by a combination of lipase-catalyzed enzymatic resolution with in situ ruthenium-catalyzed alcohol racemization is described. (R)-Selective Candida antarctica lipase B (CALB) was employed for transesterification of different fluoroaryl alcohols in DKR reactions delivering the corresponding acetates in high yield (97%) with excellent enantiomeric excess (98%).
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| 5. |
- Bogár, Krisztián, et al.
(författare)
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Hydrogenized Wilkinson´s Catalyst for Transfer Hydrogenation of Carbonyl Compounds
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Combining the advantages of homogeneous and heterogeneous catalysis is possible by heterogenization of homogeneous transition metal complexes based on a grafting/anchoring technique. Wilkinson’s catalyst ((RhCl(PPh3)3) immobilized on common silica showed high activity and selectivity in transfer hydrogenation reactions of different carbonyl compounds in isopropanol. Reactions conducted at reflux in isopropanol afforded the corresponding carbinols in high yields in short reaction times. The heterogeneous feature of the catalyst allows easy recovery and efficient reuse in the same reaction up to 5 times without loss of catalytic activity.
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| 7. |
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| 8. |
- Bogár, Krisztián, 1976-
(författare)
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Synthetic Transformations via Metal- and Enzyme-Catalyzed Dynamic Kinetic Resolution
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the preparation of a new half-sandwich type ruthenium(II)- catalyst for racemization of optically active secondary alcohols and the development of a highly efficient method in combination with lipases such as Candida antarctica lipase B and Pseudomonas cepacia lipase for dynamic kinetic resolution of various functionalized alcohols under mild reaction conditions.It was shown that the RuCl(CO)2(η5-C5Ph5) complex can racemize optically active aliphatic and aromatic secondary alcohols at room temperature in rather short times. Different parameters, such as the nature of the catalyst, catalyst loading and solvent effect were studied. After the optimization steps, the Ru-catalyzed racemization of (S)-1-phenylethanol in the presence of Candida antarctica lipase B was also investigated. The compatibility of the metal- and enzyme-catalyzed reactions led to a highly efficient coupled catalytic system for transformation of racemic alcohols to their enantiomerically pure acetates. This protocol was applied for a wide range of secondary alcohols. It was shown that in the case of allylic alcohols the obtained enantiopure allylic acetates are useful compounds for synthesis of α-methyl carboxylic acids such as (R)-Flurbiprofen and acyloin acetates. Highly selective dynamic kinetic asymmetric transformation of 3,5-piperidine diol to deliver various 3,5-dioxygenated piperidines is also described.
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| 9. |
- Csjernyik, Gábor, et al.
(författare)
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New Efficient Ruthenium Catalysts for Racemization of Alcohols at Room Temperature
- 2004
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Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 45:36, s. 6799-6802
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Tidskriftsartikel (refereegranskat)abstract
- (η5-Pentaphenylcyclopentadienyl)RuCl(CO)2 was found to catalyze efficiently the racemization of chiral alcohols such as (S)-1-phenylethanol, (S)-1-phenylpropan-2-ol, (S)-4-phenylbutan-2-ol and (S)-4-methoxy-1-phenylethanol at room temperature in the presence of a base. The catalytic activity of three other Ru(II) complexes was also investigated. The effects of halide and solvent were studied as well.
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| 10. |
- Johnston, Eric V, et al.
(författare)
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Enantioselective synthesis of (R)-bufuralol via dynamic kinetic resolution in the key step
- 2010
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society. - 0022-3263 .- 1520-6904. ; 75:13, s. 4596-4599
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Tidskriftsartikel (refereegranskat)abstract
- An enantioselective synthesis of (R)-bufuralol via a ruthenium- and enzyme-catalyzed dynamic kinetic resolution (DKR) has been achieved. The synthesis starts from readily available 2-ethylphenol and provides (R)-bufuralol in high ee and a good overall yield of 31%.
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