- The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
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A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
- Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
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p. 3665 - 3673
(2017/09/11)
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- Asymmetric synthesis and evaluation of a hydroxyphenylamide voltage-gated sodium channel blocker in human prostate cancer xenografts
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Voltage-gated sodium channels are known to be expressed in neurons and other excitable cells. Recently, voltage-gated sodium channels have been found to be expressed in human prostate cancer cells. α-Hydroxy-α- phenylamides are a new class of small molecules that have demonstrated potent inhibition of voltage-gated sodium channels. The hydroxyamide motif, an isostere of a hydantoin ring, provides an active scaffold from which several potent racemic sodium channel blockers have been derived. With little known about chiral preferences, the development of chiral syntheses to obtain each pure enantiomer for evaluation as sodium channel blockers is important. Using Seebach and Frater's chiral template, cyclocondensation of (R)-3-chloromandelic acid with pivaldehyde furnished both the cis- and trans-2,5-disubsituted dioxolanones. Using this chiral template, we synthesized both enantiomers of 2-(3-chlorophenyl)-2-hydroxynonanamide, and evaluated their ability to functionally inhibit hNav isoforms, human prostate cancer cells and xenograft. Enantiomers of lead demonstrated significant ability to reduce prostate cancer in vivo.
- Davis, Gary C.,Kong, Yali,Paige, Mikell,Li, Zhang,Merrick, Ellen C.,Hansen, Todd,Suy, Simeng,Wang, Kan,Dakshanamurthy, Sivanesan,Cordova, Antoinette,McManus, Owen B.,Williams, Brande S.,Chruszcz, Maksymilian,Minor, Wladek,Patel, Manoj K.,Brown, Milton L.
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p. 2180 - 2188
(2012/05/05)
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- Catalytic asymmetric reaction with water: Enantioselective synthesis of α-hydroxyesters by a copper-carbenoid O-H insertion reaction
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(Chemical Equation Presented) Taking on water: A novel catalytic asymmetric metal-carbenoid insertion reaction with water has been developed with copper complexes of chiral spiro bisoxazoline ligands as catalysts. This reaction provides an efficient and practical procedure for preparing chiral α-hydroxyesters and acids starting from readily available materials in high yields and enantioselectivities. BArF- = [B{3,5-(CF3)2C6H3)} 4]-.
- Zhu, Shou-Fei,Chen, Chao,Cai, Yan,Zhou, Qi-Lin
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p. 932 - 934
(2008/09/20)
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- Enantioselective homoallyl-cyclopropanation of dibenzylideneacetone by modified allylindium halide reagents-rapid access to enantioenriched 1-styryl-norcarene
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Dibenzylideneacetone (8) reacts with in situ-generated allylindium halide reagents to yield the product of a homoallyl-cyclopropanation reaction: 2-(3″-butenyl)-1,1-bis[(E)-2′-phenylethenyl]cyclopropane (9), which proceeds via step-wise cleavage of the C{double bond, long}O bond and delivery of two allyl fragments from the reagent. A range of enantiomerically enriched ligands have been tested as stoichiometric asymmetric modifiers for this process. Enantiopure compounds such as cinchona alkaloids, ephedra, aminoalcohols and tartaric acid derivatives, which have proven of utility as asymmetric modifiers for the indium-mediated allylation of aldehydes and ketones, were very inefficient in the process 8→9. However, mandelic acid derivatives, in particular mandelates, were found to be of significant potential. The absolute stereochemistry of the cyclopropane 9 has been determined by degradation to 1,1-dicarboxymethyl-2-butylcyclopropane, converging with an independent enantioselective synthesis starting from hexene. Under optimised conditions, viz. using allylindium iodide reagents and working-up with aqueous Na2SO3 to avoid iodine-mediated polymerisation, (S)-9 can be generated in 86% yield and with (S)-methyl mandelate as modifier useful enantiopurity (94/6 er) was observed. The cyclopropane product ((S)-9) undergoes RCM using standard conditions to afford a norcarene unit ((1S,6S)-1-(E)-2′-(phenylethenyl)-bicyclo[4.1.0]hept-2-ene) without loss of enantiopurity.
- Lloyd-Jones, Guy C.,Wall, Philip D.,Slaughter, Jennifer L.,Parker, Alexandra J.,Laffan, David P.
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p. 11402 - 11412
(2007/10/03)
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- Method for producing optically active mandelamide derivative and optically active phenylethanolamine derivative
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[PROBLEM TO BE SOLVED]: Though optically active mandelamide derivative and optically active phenylethanolamine derivative are useful as agrochemical intermediate,the conventional manufacturing method of them has a lot of problems. Consequently, the develo
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Page/Page column 9
(2008/06/13)
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- Preparation of (S)-mandelic acids by enantioselective degradation of racemates with a new isolate Pseudomonas putida ECU1009
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An enantioselective (R)-mandelate degrading bacterium, Pseudomonas putida ECU1009, was newly isolated from soil. The degradation activity of the bacterial cells was significantly enhanced by supplementing an optimal amount of racemic mandelic acid (0.4%), benzoylformic acid (0.4%), or benzoic acid (0.2%) to the culture medium as the enzyme inducer. Using the resting cells as a biocatalyst, three kinds of (S)-mandelic acids 1-3 were prepared with high isolated yields and enantiomeric excesses. Moreover, in a one-pot fermentation-transformation process using 1.25% (RS)-mandelic acid as the sole carbon/energy source for cultivation of the bacterium, (S)-mandelic acid 1 was accumulated after 48 h of bioconversion with 46.5% yield and >99% ee.
- Huang, Han-Rong,Xu, Jian-He,Xu, Yi,Pan, Jiang,Liu, Xiang
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p. 2113 - 2117
(2007/10/03)
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