- Readily available ruthenium complex for efficient dynamic kinetic resolution of aromatic α-hydroxy ketones
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A ruthenium complex formed from commercially available [Ru(p-cymene)Cl 2]2 and 1,4-bis(diphenylphosphino)butane catalyzes the racemization of aromatic α-hydroxy ketones very efficiently at room temperature. The racemization is fully compatible with a kinetic resolution catalyzed by a lipase from Pseudomonas stutzeri. This is the first example of dynamic kinetic resolution of α-hydroxy ketones at ambient temperature in which the metal and enzyme catalysts work in concert in one pot at room temperature to give quantitative yields of esters of α-hydroxy ketones with very high enantioselectivity.
- Agrawal, Santosh,Martinez-Castro, Elisa,Marcos, Rocio,Martin-Matute, Belen
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p. 2256 - 2259
(2014/05/06)
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- Solution-phase synthesis and evaluation of tetraproline chiral stationary phases
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A protocol was developed for the solution-phase synthesis of multigram amounts of two 9-fluorenylmethoxycarbonyl (Fmoc)-protected tetraproline peptides. These tetraproline peptides were then attached to amino derivatized silica gel. The replacement of the Fmoc group with the trimethylacetyl group lead to two tetraproline chiral stationary phases (CSPs). A comparison of the chromatographic behavior of these two solution-phase-synthesized tetraproline CSPs with that prepared by stepwise solid-phase synthesis revealed that all three had similar chromatographic performance for resolving 53 model analytes. This suggests that the solution-phase synthesis of oligoprolines, which allows for the specific benefits of good batch reproducibility, selector homogeneity, and possibly low cost, is a feasible alternative to the solid-phase synthesis of oligoproline CSPs. Copyright
- Dai, Zhi,Ye, Guozhong,Pittman Jr., Charles U.,Li, Tingyu
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experimental part
p. 329 - 338
(2012/05/20)
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- Lipase TL-mediated kinetic resolution of benzoin: Facile synthesis of (1R,2S)-erythro-2-amino-1,2-diphenylethanol
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The lipase TL-mediated kinetic resolution of (±)-benzoin (1) proceeded to give the corresponding optically pure benzoin (R)-1. On the other hand, (S)-benzoin-O-acetate (5) could be hydrolyzed without epimerization to give (S)-benzoin (S)-1, under alkaline conditions. Further, (R)-1 was converted to (1R,2S)-2-amino-1,2-diphenylethanol (99:1 er) according to the procedure reported previously. (C) 2000 Elsevier Science Ltd.
- Aoyagi, Yutaka,Agata, Naoki,Shibata, Noriko,Horiguchi, Mai,Williams, Robert M.
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p. 10159 - 10162
(2007/10/03)
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- A New General Method for the Synthesis of 4-Hydroxylated 3-Aryltetrahydroisoquinolines
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3-Aryl-4-hydroxytetrahydroisoquinolines have been prepared from deoxybenzoins.The nitrosation of the latter derivatives has been improved and the catalytic reduction of the obtained oximinoketones has been carried out with the help of ultrasounds.Heterocyclization to the isoquinoline moiety occurred on the unprotected 1,2-aminoalcohol to give stereoselectively the corresponding hydroxylated heterocycle with good yield.
- SanMartin, Raul,Olivera, Roberto,Marigorta, Eduardo Martinez de,Dominguez, Esther
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p. 5361 - 5368
(2007/10/02)
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- STEREOSELECTIVE CATALYTIC HYDROGENERATION OF alpha -HYDROXY KETOXIMES.
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Two isomers (E and Z) of benzoin oxime and 2-hydroxy-1-phenyl-1-propanone oxime were catalytically hydrogenated by using palladium on charcoal and erythro amino alcohols were obtained in about 80% diastereomeric excess. The syn-anti isomerization of these oximes in the presence of palladium on charcoal was also studied in connection with the stereoselectivity of the catalytic hydrogenation of the oximes.
- Harada,Shiono
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p. 1040 - 1045
(2007/10/02)
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