- Enzymatic Preparation of Alkanedicarboxylic Acid Monoesters
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Hydrolysis of alkanedicarboxylic acid dimethyl esters using esterase from Pseudomonas putida MR-2068 gave exclusively pure monoesters.Hydrolytic activities were dependent on the carbon chain length of the substrates.This esterase also catalyzed enantio- and regio-selective hydrolysis of α-methylalkanedicarboxylic acid dimethyl esters.
- Ozaki, Eiji,Uragaki, Toshitaka,Sakashita, Keiichi,Sakimae, Akihiro
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- Esterase catalyzed regio-and enantio-selective hydrolysis of substituted carboxylates
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Optically active α-substituted carboxylic acid derivatives were obtained with regio-and enantio-selective hydrolysis catalyzed by esterase from Pseudomonas putida MR-2068. Substrate specificities were summarized in empirical rule to predict the enantiopreferences of the esterase. High regio-selectivities were also discussed with binding models.
- Ozaki, Eiji,Sakashita, Keiichi
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- "Cofactor"-controlled enantioselective catalysis
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We report an achiral bisphosphine rhodium complex equipped with a binding site for the recognition of chiral anion guests. Upon binding small chiral guests-cofactors-the rhodium complex becomes chiral and can thus be used for asymmetric catalysis. Screening of a library of cofactors revealed that the best cofactors lead to hydrogenation catalysts that form the products with high enantioselectivity (ee?s up to 99%). Interestingly, a competition experiment shows that even in a mixture of 12 cofactors high ee is obtained, indicating that the complex based on the best cofactor dominates the catalysis.
- Dydio, Pawel,Rubay, Christophe,Gadzikwa, Tendai,Lutz, Martin,Reek, Joost N. H.
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supporting information; experimental part
p. 17176 - 17179
(2011/12/13)
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- Impact on hydrogenation catalytic cycle of the R groups Cyclic feature in "r-SMS-Phos"
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A series of R-SMS-Phos ligands was evaluated in the Rh(I)-catalyzed hydrogenation of a set of olefins showing a marked influence of the cyclic nature and structure of the R groups. Overall, cPen- and Cy-SMS-Phos performed efficiently, while Ph- and Bn-SMS-Phos exhibited slower kinetics and furnished lower ees also compared with C6F5CH2-SMS-Phos. The Rh(I)-(Cy-SMS-Phos) catalyst was screened under mild conditions displaying excellent enantioselectivities and high TOFs. Cases of catalysis under catalyst or substrate control were identified.
- Zupancic, Borut,Mohar, Barbara,Stephan, Michel
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supporting information; experimental part
p. 3022 - 3025
(2010/08/19)
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- Asymmetric synthesis of chiral glutaric acid derivatives via Rh-catalyzed enantioselective hydrogenation
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The first Rh-catalyzed enantioselective hydrogenation of dimethyl 2-methyleneglutarate and its derivatives has been reported. For the hydrogenation of dimethyl 2-methyleneglutarate with a chiral ferrocene-based monodentate phosphoramidite ligand (FAPhos), good enantioselectivity (over 90% ee) with full conversions was achieved. In contrast, the hydrogenation of substrates bearing an aryl substituent at a methylene moiety proved to be more difficult, in which the best enantioselectivity of up to 81% ee was obtained by the use of a P-stereogenic BoPhoz-type ligand.
- Duan, Zheng-Chao,Hu, Xiang-Ping,Deng, Jun,Yu, Sai-Bo,Wang, Dao-Yong,Zheng, Zhuo
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experimental part
p. 588 - 592
(2009/08/08)
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- Sesterterpenoids from the sponge Sarcotragus sp.
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Nineteen new sesterterpenoids and eight known compounds were isolated from the sponge Sarcotragus sp. collected from Soheuksan Island, Korea. The structures of these compounds were determined to be linear sesterterpenoids containing furan or related oxygenated functionalities on the basis of combined chemical and spectroscopic analyses. In addition, the configurations of several previously undetermined compounds were assigned. Several compounds exhibited moderate to major antibacterial activity (compounds 1-3, 17, 18) and cytotoxicity (3, 11, 12) against the K562 cell line and inhibitory activity against isocitrate lyase (6, 13).
- Wang, Nan,Song, Jueun,Kyoung, Hwa Jang,Lee, Hyi-Seung,Li, Xian,Oh, Ki-Bong,Shin, Jongheon
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p. 551 - 557
(2008/12/23)
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- Enzymatic resolution of (±)-5-acetoxy-4-aryl-(2E)-pentenoate derivatives
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Enzymatic resolution of six (±)-5-acetoxy-4-aryl-(2E)-pentenoate derivatives, compounds 9, 11, 13, 15, 17, and 19 bearing a different aromatic substitution pattern, using lipase OF-360 from Candida rugosa was carried out. The absolute configurations of al
- Tanikawa, Shin,Ono, Machiko,Akita, Hiroyuki
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p. 565 - 569
(2007/10/03)
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- Intramolecular reaction of a phenonium ion. Novel lactonization of 4-aryl-5-tosyloxypentanoates and 4-aryl-5-tosyloxyhexanoates concomitant with a phenyl rearrangement
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The novel lactonizations of methyl 4-aryl-5-tosyloxypentanoate 1 and 4-aryl-5-tosyloxyhexanoate 3 concomitant with a phenyl rearrangement are reported. The lactonizations were promoted by silica gel or heating in various solvents. By examining the effects of substituents of the aromatic ring on the reactivity, it was found that the reaction proceeded via a phenonium ion. This finding was supported by the stereochemical results for the lactonization of optical active 1. Silica gel-promoted lactonization of 1 gave only γ-lactone 2, whereas that of 3 afforded γ-lactone 4 and δ-lactone 5. These lactonizations proved to be kinetically controlled. On the other hand, when 3c was heated in CH3NO2 at 70°C, the highly selective formation of 4c was observed. Further detailed experiments confirmed that the thermal lactonization in CH3NO2 was thermodynamically controlled.
- Nagumo, Shinji,Ono, Machiko,Kakimoto, Yo-ichiro,Furukawa, Tsuneo,Hisano, Tomoaki,Mizukami, Megumi,Kawahara, Norio,Akita, Hiroyuki
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p. 6618 - 6622
(2007/10/03)
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- First synthesis of (+)- and (-)-elvirol based on an enzymatic function
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A highly enantioselective synthesis of versatile chiral synthons possessing one stereogenic center, (S)- and (R)-4-aryl-5-hydroxy-(2E)-pentenoate 3 was achieved based on the enzymatic reaction of (±)-4 with commercially available lipase 'OF-360' from Cand
- Ono, Machiko,Suzuki, Keiko,Tanikawa, Shin,Akita, Hiroyuki
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p. 2597 - 2604
(2007/10/03)
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