108741-13-5Relevant academic research and scientific papers
Osmium on chelate resin: Nonvolatile catalyst for the synthesis of DIOLS from alkenes
Monguchi, Yasunari,Wakayama, Fumika,Takada, Hitoshi,Sawama, Yoshinari,Sajiki, Hironao
supporting information, p. 700 - 704 (2015/03/14)
Osmium tetraoxide (OsO4) was immobilized on a commercially available chelate resin DIAION CR11 (CR11) just by simply immersing it in a methanol solution of OsO4 at room temperature. The resulting purple solid, 5% Os/CR11, indicated no volatility, and effectively catalyzed the oxidation of various alkenes to the corresponding diols.
Enantioselective bio-hydrolysis of various racemic and meso aromatic epoxides using the recombinant epoxide hydrolase Kau2
Zhao, Wei,Kotik, Michael,Iacazio, Gilles,Archelas, Alain
, p. 1895 - 1908 (2015/06/02)
Abstract Epoxide hydrolase Kau2 overexpressed in Escherichia coli RE3 has been tested with ten different racemic and meso α,β-disubstituted aromatic epoxides. Some of the tested substrates were bi-functional, and most of them are very useful building blocks in synthetic chemistry applications. As a general trend Kau2 proved to be an extremely enantioselective biocatalyst, the diol products and remaining epoxides of the bioconversions being obtained - with two exceptions - in nearly enantiomerically pure form. Furthermore, the reaction times were usually very short (around 1 h, except when stilbene oxides were used), and the use of organic co-solvents was well tolerated, enabling very high substrate concentrations (up to 75 g/L) to be reached. Even extremely sterically demanding epoxides such as cis- and trans-stilbene oxides were transformed on a reasonable time scale. All reactions were successfully conducted on a 1 g preparative scale, generating diol- and epoxide-based chiral synthons with very high enantiomeric excesses and isolated yields close to the theoretical maximum. Thus we have here demonstrated the usefulness and versatility of lyophilized Escherichia coli cells expressing Kau2 epoxide hydrolase as a highly enantioselective biocatalyst for accessing very valuable optically pure aromatic epoxides and diols through kinetic resolution of racemates or desymmetrization of meso epoxides.
Synthesis of amino thiols and isocysteines via regioselective ring opening of sulfamidates with tetrathiomolybdate
Nasir Baig,Phani Kumar,Mannuthodikayil, Jamsad,Chandrasekaran, Srinivasan
scheme or table, p. 3111 - 3118 (2011/05/17)
Herein we present a simple and highly efficient method for the synthesis of β and γ-amino thiols via regioselective ring opening of sulfamidates with tetrathiomolybdate 1. The generality of this methodology has been shown by synthesizing carbohydrate deri
Gelozymes in organic synthesis. Part IV: Resolution of glycidate esters with crude Mung bean (Phaseolus radiatus) epoxide hydrolase immobilized in gelatin matrix
Devi, Avala Vedamayee,Lahari, Challa,Swarnalatha, Lakshmi,Fadnavis
, p. 1139 - 1144 (2008/09/20)
A crude extract of Mung bean meal (Phaseolus radiatus) possessing epoxide hydrolase activity immobilized in gelatin gel (gelozyme) is employed in the stereoselective epoxide ring opening of glycidate esters. Thus, ethyl trans-(±)-3-phenyl glycidate 1a and methyl trans-(±)-3-(4-methoxyphenyl) glycidate 1b gave (2S,3R)-glycidate esters (ee >99% and 45% yield) with gelatin immobilized enzyme in diisopropyl ether. The corresponding (2R,3S)-enantiomer of 1a was hydrolyzed by an epoxide hydrolase to predominantly give the anti-product, ethyl (2R,3R)-2,3-dihydroxy-3-phenylpropanoate, with a diastereomeric excess of 78% and ee 94% (40%). A small amount (5%) of racemic syn-product was also obtained as a result of the spontaneous hydrolysis. In the case of 1b, the hydrolysis product was racemic due to high reactivity of the glycidate toward water.
NOREPINEPHRINE TRANSPORTER RADIOTRACERS AND METHODS OF SYNTHESES THEREOF
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Page/Page column 44; 45, (2008/06/13)
The present invention provides compounds and radiotracers thereof for locating, diagnosing, identifying, evaluating, detecting or quantitating NET by in vivo imaging. The invention also provides methods for locating, diagnosing, identifying, evaluating, detecting or quantitating NET, using radiotracers of high-affinity or labeled compounds of the invention, which exhibit low toxicity, can cross the blood-brain barrier and, preferably, distinguish among normal and abnormal brains. For example, a radiotracer of the invention can be administered to a patient in an amount suitable for in vivo imaging thereof. Preferably, radiotracers of the invention can also be used to locate, diagnosis, identify, evaluate, detect and quantitate NET in such diseases, disorders, conditions or maladies as, without limitation, depression, anxiety, ADHD and drug dependency.
Alkene cis-dihydroxylation by [(Me3tacn)(CF3CO 2)RuVIO2]CIO4 (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane): Structural characterization of [3 + 2] cycloadducts and kinetic studies
Yip, Wing-Ping,Yu, Wing-Yiu,Zhu, Nianyong,Che, Chi-Ming
, p. 14239 - 14249 (2007/10/03)
cis-Dioxoruthenium(VI) complex [(Me3tacn)(CF3CO 2)RuVIO2]CIO4 (1, Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) reacted with alkenes in aqueous tert-butyl alcohol to afford cis-1,2-diols in excellent yields under ambient conditions. When the reactions of 1 with alkenes were conducted in acetonitrile, oxidative C=C cleavage reaction prevailed giving carbonyl products in >90% yields without any cis-diol formation. The alkene cis-dihydroxylation and C=C cleavage reactions proceed via the formation of a [3 + 2] cycloadduct between 1 and alkenes, analogous to the related reactions with alkynes [Che et al. J. Am. Chem. Soc. 2000, 122, 11380], With cyclooctene and trans-β-methylstyrene as substrates, the Ru(III) cycloadducts [(Me3tacn)(CF 3CO2)RuIIIO(H)CH(CH2) 6HCO]CIO4 (4a) and [(Me3tacn)(CF 3CO2)RuIIIO(H)-PhCHCH(CH3)O]CIO 4 (4b) were isolated and structurally characterized by X-ray crystal analyses. The kinetics of the reactions of 1 with a series of p-substituted styrenes has been studied in acetonitrile by stopped-flow spectrophotometry. The second-order rate constants varied by 14-fold despite an overall span of 1.3 V for the one-electron oxidation potentials of alkenes. Secondary kinetic isotope effect (KIE) was observed for the oxidation of β-d2-styrene (kH/kD = 0.83 ± 0.04) and α-deuteriostyrene (kH/kD = 0.96 ± 0.03), which, together with the stereoselectivity of cis-alkene oxidation by 1, is in favor of a concerted mechanism.
Ruthenium nanoparticles supported on hydroxyapatite as an efficient and recyclable catalyst for cis-dihydroxylation and oxidative cleavage of alkenes
Ho, Chi-Ming,Yu, Wing-Yiu,Che, Chi-Ming
, p. 3303 - 3307 (2007/10/03)
Impregnation of hydroxyapatite with colloidal ruthenium results in the formation of a catalyst that effects cis-dihydroxylation and oxidative cleavage of alkenes to their respective cis-1,2-diols and carbonyl products in good to excellent yields (see scheme). The supported ruthenium catalyst can be easily recycled and reused for consecutive reaction runs without significant deterioration of the catalytic activities. R1, R2 = H, alkyl, aryl.
Electronic effects in olefin oxidation by imidoosmium(VIII) compounds
Muniz, Kilian
, p. 2243 - 2252 (2007/10/03)
Imido osmium(VIII) complexes are versatile oxidants for C-C double bond functionalisation. Despite their structural similarity with OsO4 their reactivity cannot always be compared with this seminal reagent. Detailed investigations including kinetic competition experiments are presented that uncover the electronic and steric preferences of osmium imido complexes. The different behaviour of OsO4 and its imido derivatives towards tertiary amines and diamines is clarified. Hammett correlation studies reveal that the reactivity spectrum of the respective oxidants ranges from a strongly electrophilic behaviour in the case of OsO4 to a rather nucleophilic character as encountered for OsO(NtBu)3. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Direct catalytic asymmetric aldol-type reaction of aldehydes with ethyl diazoacetate
Yao, Wengang,Wang, Jianbo
, p. 1527 - 1530 (2007/10/03)
(Matrix presented) The direct aldol-type condensation of aldehydes with ethyl diazoacetate catalyzed by the chiral complex of BINOL derivatives-Zr(OtBu)4 gave β-hydroxy α-diazo carbonyl compounds with moderate enantioselectivities (5
Stereoselective and regioselective reaction of cyclic ortho esters with phenols
Bozell,Miller,Hames,Loveless
, p. 3084 - 3089 (2007/10/03)
Cyclic ortho esters undergo stereoselective and regioselective reaction with phenols when treated with BF3·OEt2 at low temperatures. Attack of the phenol on the ortho ester occurs at an open carbon para to electron-donating groups on the phenol ("C-addition") or at the phenolic hydroxyl group ("O-addition") depending on the nature of the cation formed from reaction of the ortho ester and BF3·OEt2. Products resulting from O-addition undergo reversion to a mixture of starting phenol, C-addition product, and O-addition product if treated with BF3·OEt2 at room temperature, but C-addition products are stable under the same conditions. X-ray structural analysis of the C-addition compound indicates that its stereochemistry is opposite to that observed in reaction of similar ortho esters with chloride from TMSCl. However, the stereochemistry of the reaction can be rationalized by the ability of the ortho ester to isomerize via an intermediate benzylic cation and examination of the preferred trajectory of attack of the nucleophile on the intermediate oxonium ion.
