1517-69-7Relevant articles and documents
Palladium catalysed mono-N-arylation of enantiopure diamines
Frost, Christopher G.,Mendonca, Paul
, p. 1831 - 1834 (1999)
The palladium catalysed arylation of amines is employed to prepare selectively a range of new, mono-N-arylated, enantiopure diamine ligands. The ligands were tested in the catalytic asymmetric transfer hydrogenation of acetophenone.
ASYMMETRIC SYNTHESIS XXI. ENANTIOSELECTIVE REDUCTION OF KETONES CATALYZED BY NEW (4S,5R)-4,5-DIPHENYL-1,3,2-OXAZABOROLIDINE
Yaozhong, Jiang,Yong, Qin,Aiqiao, Mi,Zhitang, Huang
, p. 1211 - 1214 (1994)
Oxazaborolidine prepared from (1R,2S)-1,2-diphenyl-2-aminoethanol with borane was used as catalyst in the enantioselective reduction of ketones.Excellent enantioselectivities with e.e. >99percent for acetophenone and e.e. >96percent for ω-bromo-acetophenone have been achieved.
Enantiodivergent asymmetric catalysis with the tropos BIPHEP ligand and a proline derivative as chiral selector
Oczipka,Müller,Leitner,Franciò
, p. 678 - 683 (2016)
A catalytic system based on the tropos ligand BIPHEP and (S)-proline methyl ester as chiral selector was studied for Rh-catalysed asymmetric catalysis. By careful control of the catalyst preformation conditions, the enantioselectivity could be completely reversed in asymmetric hydrogenation of prochiral olefins maintaining the same absolute level in favorable cases. The enantiodivergent asymmetric catalysis could be rationalised by the interplay of the dynamic chirality (tropos) of the phosphine ligand and the coordination of the proline selector. Treating a suitable Rh-BIPHEP precursor with the (Sc)-proline-based ionic liquid led to an equimolar mixture of (RaSc)- and (SaSc)-diastereomers that is kinetically stable at 0 °C. At higher temperature, an irreversible diastereomerisation process was observed resulting in the diastereomerically pure (RaSc)-complex [Rh{(Ra)-BIPHEP}{(Sc)-ProlOMe}]. Whereas the use of the pure (RaSc)-complex led to 51% ee (R) in the hydrogenation of methyl 2-acetamidoacrylate, the S-product was formed with almost identical enantioselectivity when the (RaSc)/(SaSc)-mixture was applied under identical conditions. This inversion was associated with the relative stability of the diastereomers in the equilibria forming the catalytically active substrate complex. The possibility to use this different reactivity to control the direction of enantioselectivity was demonstrated for the hydrogenation of different substrates whereby ee's of up to 80% could be achieved. Moreover, the (RaSc)-complex led to high enantioselectivities of up 86% ee in the asymmetric hydroboration of styrene, approaching the performance of the atropos BINAP ligand for this reaction.
Oxazaborolidine Catalyzed Borane Reductions of Ketones: A Significant Effect of Temperature on Selectivity
Stone, Guy B.
, p. 465 - 472 (1994)
The effect of temperature on the selectivity of oxazaborolidine catalyzed borane reductions of ketones has been studied.For two model ketones acetophenone (2a) and cyclohexylmethyl ketone (2b), and two different oxazaborolidine catalysts derived from n-b
Combined microbial oxidation and reduction: A new approach to the high-yield synthesis of homochiral unsaturated secondary alcohols from racemates
Fantin,Fogagnolo,Giovannini,Medici,Pedrini
, p. 3047 - 3053 (1995)
The oxidation of racemic secondary alcohols with Bacillus stearothermophilus followed by reduction of the mixture with Yarrowia lipolytica to afford high yields of the enantiomerically pure R-alcohols 1a,b,d is described. Comparisons with Yarrowia lipolytica reduction, Bacillus stearothermophilus oxidation, and the contemporary use of the two microorganisms have been made.
Mechanism of Asymmetric Hydrogenation of Aromatic Ketones Catalyzed by a Combined System of Ru(π-CH2C(CH3)CH2)2(cod) and the Chiral sp2N/sp3NH Hybrid Linear N4 Ligand Ph-BINAN-H-Py
Nakatsuka, Hiroshi,Yamamura, Tomoya,Shuto, Yoshihiro,Tanaka, Shinji,Yoshimura, Masahiro,Kitamura, Masato
, p. 8138 - 8149 (2015)
The combination of a Goodwin-Lions-type chiral N4 ligand, (R)-Ph-BINAN-H-Py ((R)-3,3′-diphenyl-N2,N2′-bis((pyridin-2-yl)methyl)-1,1′-binaphthyl-2,2′-diamine; L), with Ru(π-CH2C(CH3)CH2)2(co
Plasma-Driven in Situ Production of Hydrogen Peroxide for Biocatalysis
Alcalde, Miguel,Bandow, Julia E.,Baraibar, álvaro Gómez,Fueyo, Elena Fernandez,Hollmann, Frank,Kourist, Robert,Krewing, Marco,Yayci, Abdulkadir
, (2020)
Peroxidases and peroxygenases are promising classes of enzymes for biocatalysis because of their ability to carry out one-electron oxidation reactions and stereoselective oxyfunctionalizations. However, industrial application is limited, as the major drawback is the sensitivity toward the required peroxide substrates. Herein, we report a novel biocatalysis approach to circumvent this shortcoming: in situ production of H2O2 by dielectric barrier discharge plasma. The discharge plasma can be controlled to produce hydrogen peroxide at desired rates, yielding desired concentrations. Using horseradish peroxidase, it is demonstrated that hydrogen peroxide produced by plasma treatment can drive the enzymatic oxidation of model substrates. Fungal peroxygenase is then employed to convert ethylbenzene to (R)-1-phenylethanol with an ee of >96 % using plasma-generated hydrogen peroxide. As direct treatment of the reaction solution with plasma results in reduced enzyme activity, the use of plasma-treated liquid and protection strategies are investigated to increase total turnover. Technical plasmas present a noninvasive means to drive peroxide-based biotransformations.
An immobilized lipase microfluidic reactor for enantioselective hydrolysis of ester
Gao, Yan,Zhong, Runtao,Qin, Jianhua,Lin, Bingcheng
, p. 262 - 263 (2009)
Enantioselective enzymatic hydrolysis of racemic mixture is an effective method to obtain pure enantiomer. In this report, an immobilized lipase microfluidic reactor was fabricated and applied to enantioselective hydrolysis of racemic 1-phenylethyl acetate to obtain (R)-l-phenylethanol. This immobilized lipase microfluidic reactor consumed trace amount of enzyme, showed identical performance compared to free enzyme in batch, and good stability that can be recycled for at least eight times without obvious loss of activity. Copyright
Cascading g-C3N4 and Peroxygenases for Selective Oxyfunctionalization Reactions
Van Schie, Morten M.C.H.,Zhang, Wuyuan,Tieves, Florian,Choi, Da Som,Park, Chan Beum,Burek, Bastien O.,Bloh, Jonathan Z.,Arends, Isabel W. C. E.,Paul, Caroline E.,Alcalde, Miguel,Hollmann, Frank
, p. 7409 - 7417 (2019)
Peroxygenases are very interesting catalysts for specific oxyfunctionalization chemistry. Instead of relying on complicated electron transport chains, they rely on simple hydrogen peroxide as the stoichiometric oxidant. Their poor robustness against H2O2 can be addressed via in situ generation of H2O2. Here we report that simple graphitic carbon nitride (g-C3N4) is a promising photocatalyst to drive peroxygenase-catalyzed hydroxylation reactions. The system has been characterized by outlining not only its scope but also its current limitations. In particular, spatial separation of the photocatalyst from the enzyme is shown as a solution to circumvent the undesired inactivation of the biocatalyst. Overall, very promising turnover numbers of the biocatalyst of more than 60.000 have been achieved.
Mapping the substrate selectivity and enantioselectivity of esterases from thermophiles
Somers, Neil A.,Kazlauskas, Romas J.
, p. 2991 - 3004 (2004)
To identify potential applications of nineteen esterases from thermophiles, we mapped their substrate selectivity and enantioselectivity using a library of 50 esters. We measured the selectivities colorimetrically using Quick E, which uses pH indicators to detect hydrolysis and a chromogenic reference compound as an internal control. The substrate selectivity mapping revealed one esterase, E018b, with a strong preference for acetyl esters (14- to 25-fold over hexanoate). The enantioselectivity mapping revealed a number of cases of high enantioselectivity. Thirteen of the 19 esterases showed moderate or better enantioselectivity (>19) toward 1-phenethyl butyrate favoring the (R)-enantiomer and two esterases (E008, E013) showed moderate or better enantioselectivity (>20) toward methyl 2-chloropropionate favoring the (S)-enantiomer. Three esterases (E001, E004, E005) showed high (>46) enantioselectivity toward menthyl acetate favoring the (R)-enantiomer. This rapid mapping of the selectivity simplifies the characterization of new enzymes.
New chiral phosphorus catalysts derived from (S)-binaphthol for highly enantioselective reduction of acetophenone by borane
Ma, Margaret F. P.,Li, Kangying,Zhou, Zhenghong,Tang, Chuchi,Chan, Albert S. C.
, p. 3259 - 3261 (1999)
New chiral (+)-2,2'-O,O-(1,1'-binaphthyl)-dioxo-N,N-diethylphospholidine 1 and its borane complex 3 were prepared from (S)-binaphthol and their use as catalysts in enantioselective borane reductions of prochiral acetophenone were investigated. Enantiomeri
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Boireau,G. et al.
, p. 1457 - 1461 (1979)
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Discovery and Redesign of a Family VIII Carboxylesterase with High (S)-Selectivity toward Chiral sec-Alcohols
Park, Areum,Park, Seongsoon
, p. 2397 - 2402 (2022/02/17)
Highly enantioselective lipase has been widely utilized in the preparation of versatile enantiopure chiral sec-alcohols through kinetic or dynamic kinetic resolution. Lipase is intrinsically (R)-selective, and it is difficult to obtain (S)-selective lipase. Recent crystal structures of a family VIII carboxylesterase have revealed that the spatial array of its catalytic triad is the mirror image of that of lipase but with a catalytic triad that is distinct from lipase. We, therefore, hypothesized that the family VIII carboxylesterase may exhibit (S)-enantioselectivity toward sec-alcohols similar to (S)-selective serine protease, whose catalytic triad is also spatially arrayed as its mirror image. In this study, a homologous enzyme (carboxylesterase from Proteobacteria bacterium SG_bin9, PBE) of a known family VIII carboxylesterase (pdb code: 4IVK) was prepared, which showed not only moderate (S)-selectivity toward sec-alcohols such as 3-butyn-2-ol and 1-phenylethyl alcohol but also (R)-selectivity toward particular sec-alcohols among the substrates explored. Furthermore, the (S)-selectivity of PBE has been significantly improved by rational redesign based on molecular modeling. Molecular modeling identified a binding pocket composed of Ser381, Ala383, and Arg408 for the methyl substituent of (R)-1-phenylethyl acetate and suggested that larger residues may increase the enantioselectivity by interfering with the binding of the slow-reacting enantiomer. As predicted, substituting Ser381with larger residues (Phe, Tyr, and Trp) significantly improved the (S)-selectivity of PBE toward all sec-alcohols explored, even the substrates toward which the wild-type PBE exhibits (R)-selectivity. For instance, the enantioselectivity toward 3-butyn-2-ol and 1-phenylethyl alcohol was improved from E = 5.5 and 36.1 to E = 2001 and 882, respectively, by single mutagenesis (S381F).
Chromoselective Photocatalysis Enables Stereocomplementary Biocatalytic Pathways**
Schmermund, Luca,Reischauer, Susanne,Bierbaumer, Sarah,Winkler, Christoph K.,Diaz-Rodriguez, Alba,Edwards, Lee J.,Kara, Selin,Mielke, Tamara,Cartwright, Jared,Grogan, Gideon,Pieber, Bartholom?us,Kroutil, Wolfgang
supporting information, p. 6965 - 6969 (2021/03/03)
Controlling the selectivity of a chemical reaction with external stimuli is common in thermal processes, but rare in visible-light photocatalysis. Here we show that the redox potential of a carbon nitride photocatalyst (CN-OA-m) can be tuned by changing the irradiation wavelength to generate electron holes with different oxidation potentials. This tuning was the key to realizing photo-chemo-enzymatic cascades that give either the (S)- or the (R)-enantiomer of phenylethanol. In combination with an unspecific peroxygenase from Agrocybe aegerita, green light irradiation of CN-OA-m led to the enantioselective hydroxylation of ethylbenzene to (R)-1-phenylethanol (99 % ee). In contrast, blue light irradiation triggered the photocatalytic oxidation of ethylbenzene to acetophenone, which in turn was enantioselectively reduced with an alcohol dehydrogenase from Rhodococcus ruber to form (S)-1-phenylethanol (93 % ee).
