- Oxidation of Vicinal Diols to α-Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst
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α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to α-hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions.
- Mecozzi, Francesco,Dong, Jia Jia,Saisaha, Pattama,Browne, Wesley R.
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supporting information
p. 6919 - 6925
(2017/12/26)
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- Genome mining for innovative biocatalysts: New Dihydroxyacetone aldolases for the chemist's toolbox
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Stereoselective carboligating enzymes were discovered by a genome mining approach to extend the biocatalysis toolbox. Seven hundred enzymes were selected by sequence comparison from diverse prokaryotic species as representatives of the aldolase (FSA) family diversity. The aldol reaction tested involved dihydroxyacetone (DHA) and glyceraldehyde-3-phosphate. The hexose-6-phosphate formation was monitored by mass spectrometry. Eighteen enzymes annotated either as transaldolases or aldolases were found to exhibit a DHA aldolase activity. Remarkably, six of them proven as aldolases, and not transaldolases, shared very limited similarities with those currently described. Multiple sequence alignment performed on all enzymes revealed a Tyr in the new DHA aldolases as found in FSAcoli instead of a Phe usually found in transaldolases. Four of these DHA aldolases were biochemically characterised in comparison with FSAcoli. In particular, an aldolase from Listeria monocytogenes exhibited interesting catalytic properties. Exploiting nature′s catalyst mines: A universal high-throughput screening strategy based on mining genomes and selection of enzyme representatives of the aldolase family is applied. Out of ten hits proven as dihydroxyacetone aldolases, one from Listeria monocytogenes exhibited highly interesting catalytic properties, comparable to those of FSAcoli.
- Guérard-Hélaine, Christine,De Berardinis, Véronique,Besnard-Gonnet, Marielle,Darii, Ekaterina,Debacker, Marine,Debard, Adrien,Fernandes, Carlos,Hélaine, Virgil,Mariage, Aline,Pellouin, Virginie,Perret, Alain,Petit, Jean-Louis,Sancelme, Martine,Lemaire, Marielle,Salanoubat, Marcel
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p. 1871 - 1879
(2015/06/23)
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- Chemoselective oxidation of polyols with chiral palladium catalysts
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Chiral palladium-based catalysts derived from pyridinyl oxazoline (pyOx) ligands catalyze the oxidation of alcohols, including 1,2-diols, triols, and tetraols, with high regio- and chemoselectivity. Screening of various chiral oxazoline-derived ligands for the oxidation of a model diol, 1,2-propanediol (1,2-PD), revealed that the nature of the ligand had a significant influence on the activity and chemoselectivity for oxidation of vicinal diols. The PyOx ligands containing an α-methyl substituent were the most active for the oxidation of 1,2-PD using benzoquinone as the terminal oxidant. Oxidation of vicinal diols and polyols occurs selectively at the secondary alcohol to afford α-hydroxy ketones in isolated yields of 62-87%. Chemoselective oxidation of meso-erythritol with the chiral [(S)-(α-Me(tert-Bu)PyOx)Pd(OAc)] 2[OTf]2 afforded (S)-erthyrulose in 62% yield and 24% ee.
- De Crisci, Antonio G.,Chung, Kevin,Oliver, Allen G.,Solis-Ibarra, Diego,Waymouth, Robert M.
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p. 2257 - 2266
(2013/05/21)
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- Chemoselective Pd-catalyzed oxidation of polyols: Synthetic scope and mechanistic studies
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The regio- and chemoselective oxidation of unprotected vicinal polyols with [(neocuproine)Pd(OAc)]2(OTf)2 (1) (neocuproine = 2,9-dimethyl-1,10-phenanthroline) occurs readily under mild reaction conditions to generate α-hydroxy ketones. The oxidation of vicinal diols is both faster and more selective than the oxidation of primary and secondary alcohols; vicinal 1,2-diols are oxidized selectively to hydroxy ketones, whereas primary alcohols are oxidized in preference to secondary alcohols. Oxidative lactonization of 1,5-diols yields cyclic lactones. Catalyst loadings as low as 0.12 mol % in oxidation reactions on a 10 g scale can be used. The exquisite selectivity of this catalyst system is evident in the chemoselective and stereospecific oxidation of the polyol (S,S)-1,2,3,4-tetrahydroxybutane [(S,S)-threitol] to (S)-erythrulose. Mechanistic, kinetic, and theoretical studies revealed that the rate laws for the oxidation of primary and secondary alcohols differ from those of diols. Density functional theory calculations support the conclusion that β-hydride elimination to give hydroxy ketones is product-determining for the oxidation of vicinal diols, whereas for primary and secondary alcohols, pre-equilibria favoring primary alkoxides are product-determining. In situ desorption electrospray ionization mass spectrometry (DESI-MS) revealed several key intermediates in the proposed catalytic cycle.
- Chung, Kevin,Banik, Steven M.,De Crisci, Antonio G.,Pearson, David M.,Blake, Timothy R.,Olsson, Johan V.,Ingram, Andrew J.,Zare, Richard N.,Waymouth, Robert M.
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supporting information
p. 7593 - 7602
(2013/07/05)
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- Microbial Transformation of sec-Hydroxyl Group of Polyols into Carbonyl Derivatives by Specific Oxidation Using Methanol Yeast
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sec-Hydroxyl group of polyol was oxidized to the corresponding carbonyl derivative using methanol yeast, Candida boidinii KK912.Thus 1,2,4-butanetriol was oxidized for 2 days to give 1,4-dihydroxy-2-butanone in 78.1percent yield.The microbial oxidation for analogous polyols was also discussed.
- Matsumura, Shuichi,Kawamori, Tomoko,Yoshikawa, Sadao
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p. 729 - 730
(2007/10/02)
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- Synthesis and Coordinating Properties of Ligands Designed for Modeling of the Active Site Zinc of Liver Alcohol Dehydrogenase
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Some tridentate ligands have been prepared for coordination of zinc(II) ions (or cobalt(II), which acts as a surrogate for Zn(II) ions) in a manner analogous to the coordination found in liver alcohol dehydrogenase.This entails coordination of the metal ion to two thiolates and an imidazole.The ligands must be sufficiently sterically hindered to prevent thiolate from acting as a bridging ligand between two metal ions.For some aspects of this work pyridine was used instead of imidazole.A trisubstituted benzene derivative, 3,5-bis(3-mercaptopropoxy)-N-benzamide (7) was prepared.Zn(II) complexes with 7 could not be characterized but the Co(II) complexes showed excellent spectral correlation with liver alcohol dehydrogenase in which Zn(II) has been replaced by Co(II).Several analogues of 7 have also been synthesized.Another ligand, 2,6-bispyridine (17), does provide a monomeric Zn(II) complex.The synthesis and coordination of various analogues of this system have been examined.The bis-alcohol, 2,6-bis(2-methyl-2-hydroxypropyl)pyridine (24), gives a stable pentacoordinate complex with Zn(NO3)2 and two water molecules.
- Kaptein, Bernard,Barf, G.,Kellogg, Richard M.,Bolhuis, F. Van
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p. 1890 - 1901
(2007/10/02)
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- 2(E)-(4-Methyl-3-pentenylidene)-butanedial, β-Acaridial: A New Type of Monoterpene from the Mold Mite Tyrophagus putrescentiae (Acarina, Acaridae)
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The natural product chemistry of opisthonotal gland excretion was studied for the mold mite Tyrophagus putrescentiae.The secretion contained a new type of monoterpene dial, 2(E)-(4-methyl-3-pentenylidene)-butanedial (1), which we gave the trivial name β-a
- Leal, Walter Soares,Kuwahara, Yasumasa,Suzuki, Takahisa
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p. 875 - 878
(2007/10/02)
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- Mechanism for the Hydrolytic Degradation of Barban to 3-Chloroaniline
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4-Chloro-2-butynyl N-(3-chlorophenyl)carbamate (Barban) is a herbicide whose alkaline hydrolysis leads quantitatively to 3-chloroaniline, after releasing the chlorine atom from the ester group.The dechlorination step proceeds via a nucleophilic substitution reaction of the type SN2-SN2', corresponding to an attack by hydroxide ion at the carbon atoms that are α and γ to the chlorine atom.The 4-hydroxy-2-butynyl and 2-oxo-3-butenyl N-(3-chlorophenyl)carbamates thus formed are hydrolysed to the N-(3-chlorophenyl)carbamic acid which, on decarboxylation, gives 3-chloroaniline.
- Bergon, M.,Kouda-Bonafos, M.,Calmon, J. P.
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p. 1915 - 1920
(2007/10/02)
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- β1-Selective Adrenoceptor Antagonists: Examples of the 2-phenyl>imidazole Class. 2
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An attempt to develop a highly cardioselective β-adrenoceptor antagonist devoid of intrinsic sympathomimetic activity (ISA) focused on exploring structure-activity relationships around (S)--amino>-2-hydroxypropoxy>phen
- Baldwin, John J.,Christy, Marcia E.,Denny, George H.,Habecker, Charles N.,Freedman, Mark B.,et al.
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p. 1065 - 1080
(2007/10/02)
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- Radical-Induced Dephosphorylation of Fructose Phosphates in Aqueous Solution
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Oxygen free N2O-saturated aqueous solutions of D-fructose-1-phosphate and D-fructose-6-phosphate were γ-irradiated.Inorganic phosphate and phosphate free sugars (containing four to six carbon atoms) were identified and their G-values measured.D-Fructose-1-phosphate yields (G-values in parentheses) inorganic phosphate (1.6), hexos-2-ulose (0.12), 6-deoxy-2,5-hexodiulose (0.16), tetrulose (0.05) and 3-deoxytetrulose (0.15).D-Fructose-6-phosphate yields inorganic phosphate (1.7), hexos-5-ulose (0.1), 6-deoxy-2,5-hexodiulose (0.36), 3-deoxy-2,5-hexodiulose and 2-deoxyhexos-5-ulose (together 0.18).On treatment with alkaline phosphate further deoxy sugars were recognized and in fructose-1-phosphate G(6-deoxy-2,5-hexodiulose) was increased to a G-value of 0.4.Dephosphorylation is considered to occur mainly after OH attack at C-5 and C-1 in fructose-1-phosphate and at C-5 and C-6 in fructose-6-phosphate.Reaction mechanisms are discussed. - Keywords: D-Fructose-1-phosphate, D-Fructose-6-phosphate, γ-Irradiation; Radical Reactions, Mass Spectrometry
- Zegota, Henryk,Sonntag, Clemens von
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p. 1331 - 1337
(2007/10/02)
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