- Chiroptical properties of 2,2’-bioxirane
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The two enantiomers of 2,2′-bioxirane were synthesized, and their chiroptical properties were thoroughly investigated in various solvents by polarimetry, vibrational circular dichroism (VCD), and Raman optical activity (ROA). Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVTZ level revealed the presence of three conformers (G+, G?, and cis) with Gibbs populations of 51, 44, and 5% for the isolated molecule, respectively. The population ratios of the two main conformers were modified for solvents exhibiting higher dielectric constants (G? form decreases whereas G+ form increases). The behavior of the specific optical rotation values with the different solvents was correctly reproduced by time-dependent DFT calculations using the polarizable continuum model (PCM), except for the benzene for which explicit solvent model should be necessary. Finally, VCD and ROA spectra were perfectly reproduced by the DFT/PCM calculations for the Boltzmann-averaged G+ and G? conformers.
- Daugey,De Rycke,Brotin,Buffeteau
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p. 342 - 350
(2018/01/15)
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- Carbonylation of functionalized diamine diols to cyclic ureas: Application to derivatives of DMP 450
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Synthesis of the cyclic urea core structure of the HIV protease inhibitor DMP 450 has been achieved via W(CO)6/I2-catalyzed carbonylation of diamine intermediates. Carbonylations of related functionalized diamines to derivatives of the DMP 450 core structure were also examined. Selected diamine diol substrates could be converted to the cyclic urea core structure by catalytic carbonylation without protection of the diol functionality.
- Darko, Ampofo K.,Curran, F. Chris,Copin, Chloé,McElwee-White, Lisa
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experimental part
p. 3976 - 3983
(2011/06/25)
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- METHOD FOR REPROCESSING MIXTURES CONTAINING BIS-EPOXIDE
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The invention relates to a method for reprocessing mixtures containing (a) one or several bis-epoxides of general formula (I), wherein R1 and R2 are identical or different and are selected among hydrogen and C1-C3 alkyl, (b) one or several organic solvents, (c) water, and (d) other optional compounds. The inventive method is characterized in that the mixture is subjected to an at least two-stage distillation process, at least one bis-epoxide (a) being converted into the gas phase in at least one stage.
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Page/Page column 11-13
(2008/06/13)
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- METHOD FOR THE PRODUCTION OF BISEPOXIDES AND DITHIOLS
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The invention relates to a method for the production of bisepoxides, characterised in that a conjugated diene of formula (I) is reacted with at least one peroxide with the application of up to 4 equivalents of peroxide per C-C double bond, where R1 is selected from hydrogen and C1-C12 alkyl, unsubstituted or substituted with one or several SH or OH groups, in the presence of a catalyst, obtained by the bringing into contact of at least one manganese compound, selected from A2MnX4, AMnX3, MnY, MnX2 and MnX3 with at least one ligand L, of general formula (II), whereby the variables have the following definitions: X may be the same or different and is selected from monovalent anions, Y is a divalent anion, A is selected from alkali metals and optionally alkylated ammonium, R2 may be different or preferably the same and selected from C1-C20 alkyl and at least one co-ligand, derived from monocarboxylic acids, di- or poly-carboxylic acids or diamines.
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Page/Page column 16; 17
(2008/06/13)
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- Interstrand and intrastrand DNA-DNA cross-linking by 1,2,3,4-diepoxybutane: Role of stereochemistry
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1,2,3,4-Diepoxybutane (DEB) is a bifunctional electrophile capable of forming DNA-DNA and DNA-protein cross-links. DNA alkylation by DEB produces N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)-guanine monoadducts, which can then form 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) lesions. All three optical isomers of DEB are produced metabolically from 1,3-butadiene, but S,S-DEB is the most cytotoxic and genotoxic. In the present work, interstrand and intrastrand DNA-DNA cross-linking by individual DEB stereoisomers was investigated by PAGE, mass spectrometry, and stable isotope labeling. S,S-, R,R-, and meso-diepoxides were synthesized from L-dimethyl-2,3-O-isopropylidene-tartrate, D-dimethyl-2,3-O-isopropylidene- tartrate, and meso-erythritol, respectively. Total numbers of bis-N7G-BD lesions (intrastrand and interstrand) in calf thymus DNA treated separately with S,S-, R,R-, or meso-DEB (0.01-0.5 mM) were similar as determined by capillary HPLC-ESI+-MS/MS of DNA hydrolysates. However, denaturing PAGE has revealed that S,S-DEB produced the highest number of interchain cross-links in 5′-GGC-3′/3′-CCG-5′ sequences. Intrastrand adduct formation by DEB was investigated by a novel methodology based on stable isotope labeling HPLC-ESI+-MS/MS. Meso DEB treatment of DNA duplexes containing 5′-[1,7, NH2-15N3,2- 13C-G]GC-3′/3′-CCG-5′ and 5′-GGC-3′/ 3′-CC[15N3,2-13C-G]-5′ trinucleotides gave rise to comparable numbers of 1,2-intrastrand and 1,3-interstrand bis-N7G-BD cross-links, while S,S DEB produced few intrastrand lesions. R,R-DEB treated DNA contained mostly 1,3-interstrand bis-N7G-BD, along with smaller amounts of 1,2-interstrand and 1,2-intrastrand adducts. The effects of DEB stereochemistry on its ability to form DNA-DNA cross-links may be rationalized by the spatial relationships between the epoxy alcohol side chains in stereoisomeric N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)- guanine adducts and their DNA environment. Different cross-linking specificities of DEB stereoisomers provide a likely structural basis for their distinct biological activities.
- Park, Soobong,Anderson, Christopher,Loeber, Rachel,Seetharaman, Mahadevan,Jones, Roger,Tretyakova, Natalia
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p. 14355 - 14365
(2007/10/03)
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- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
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The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
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p. 1307 - 1315
(2007/10/03)
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- Multigram-scale stereoselective synthesis of meso-1,3-butadiene bisepoxide
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meso-1,3-Butadiene bisepoxide, a potential building block for natural product synthesis and of interest as a toxic metabolite of butadiene, was synthesized in multi-gram scale in two steps from meso-erythritol in good overall yield.
- Claffey, David J.
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p. 3041 - 3045
(2007/10/03)
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- Method for production of oxygen-containing organic compound
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A novel method for the production of an oxygen-containing organic compound is provided. The production of an oxygen-containing organic compound is attained by oxidizing an olefin, an alcohol, or an aldehyde by catalyzing thereof with a molecular oxygen-containing gas in the presence of a catalyst formed of a polyoxo metalate substituted with a divalent transition metal cation.
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- Raman, infrared, and microwave spectra and conformational preferences of meso-Bisoxirane
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Vibrational infrared and Raman spectra of liquid and solid meso-bisoxirane and infrared spectra of the gaseous phase were recorded. Additionally, microwave rotational spectra from 40 to 18 GHz were recorded. The vibrational spectra demonstrate the presence of two conformations in the fluid phases but only one in the solid state. Infrared and Raman activities and gas-phase band contours indicate that the trans conformer with C(i) molecular symmetry is more stable than the gauche conformer (C1 symmetry). Variable temperature studies of two pairs of Raman lines are consistent with a ΔH value of 0.31 ± 0.10 kcal/mol in the liquid state. Rotational constants (A = 9187.45 ± 0.04, B = 2651.80 ± 0.01, C = 2608.92 ± 0.01 MHz) and the dipole moment (μ(total) = 3.03 D) were determined for the gauche conformer. Model calculations give an acceptable match to the observed rotational constants for an H-C-C'-H' dihedral angle of 60°. The relationship of meso-bisoxirane to other similar three-membered ring compounds is discussed. Published by Elsevier Science B.V.
- Kalasinsky,Subramaniam,Su,Cook
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p. 521 - 530
(2007/10/03)
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- Persistence of N7-(2,3,4-trihydroxybutyl)guanine adducts in the livers of mice and rats exposed to 1,3-butadiene
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Liquid chromatography (LC) in combination with tandem mass spectrometry (MS/MS) and stable isotope methodology was employed for the analysis of the N7-guanine (Gua) adducts derived from 1,2:3,4-diepoxybutane (BDO2) a reactive metabolite of 1,3-butadiene (BD). Two diastereomeric forms of N7- (2,3,4-trihydroxybutyl)guanine (THBG) were identified in the livers of both mice and rats. One of the diastereomers [(±)-THBG] was formed by reaction of DNA with (±)-BDO2, and the other diastereomer (meso-THBG) was formed by reaction of DNA with meso-BDO2. There was significantly more (±)-THBG and meso-THBG in the liver DNA of the mice when compared with those of the rats during the 10 days of exposure to BD and the 6 days of postexposure that were monitored. There was a 2-fold excess of (±)-THBG over meso-THBG in the rat liver at all the time points. In the mouse liver after 10 days of exposure to BD, the (±)-THBG (3.9 adducts/106 normal bases) was also present in an almost 2-fold excess over meso-THBG (2.2 adducts/106 normal bases). However, 6-days after exposure to BD, (±)THBG (1.2 adducts/106 normal bases) and meso-THBG (1.0 adduct/106 normal bases) were present in almost equal amounts in the mouse liver. Furthermore, there was an almost 5-fold excess of the two THBG diastereomers in the mouse liver DNA 6 days after exposure to BD when compared with rat liver DNA. The half-lives of (±)-THBG and meso-THBG appeared to be slightly longer in mouse liver (4.1 and 5.5 days, respectively) than in rat liver (3.6 and 4.0 days, respectively). The apparent persistence of these adducts in the mouse may contribute to the increased susceptibility of this species to BD-induced carcinogenesis. It is possible that (±)-THBG and meso-THBG could have also been derived from the reaction of DNA with the hydrolysis product of BDO2, 1,2-dihydroxy-3,4- epoxybutane (DHEB). Surprisingly, a vast majority of the studies in which the mutagenic and carcinogenic potential of BDO2 have been examined have only employed the commercially available (±)-BDO2. In light of the present findings, additional studies will be required to determine the potency of meso-BDO2 and the DHEB that is the precursor to meso-THBG as mutagens and carcinogens.
- Oe, Tomoyuki,Kambouris, Sara J.,Walker, Vernon E.,Meng, Quanxin,Recio, Leslie,Wherli, Suzanne,Chaudhary, Ajai K.,Blair, Ian A.
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p. 247 - 257
(2007/10/03)
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- Epoxidation of terminal or electron-deficient olefins with H2O2, catalysed by Mn-trimethyltriazacyclonane complexes in the presence of an oxalate buffer
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A catalytic amount of an oxalate/oxalic acid buffer strongly enhances the catalytic properties of Mn-tmtacn complexes for epoxidation reactions with H2O2. Especially terminal olefins are easily epoxidized. Yields for e.g. allyl acetate or 1-hexene reach up to 99 % and 65 % on olefin and peroxide basis respectively. The reaction is stereospecific; there are no products of solvolysis.
- De Vos, Dirk E.,Sels, Bert F.,Reynaers, Mattias,Subba Rao,Jacobs, Pierre A.
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p. 3221 - 3224
(2007/10/03)
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- Synthesis of 1,2,3,4-diepoxybutane from 1,3-butadiene monoxide
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The possibility of producing 1,2,3,4-diepoxybutane by the epoxidation of 1,3-butadiene monoxide with tert-butylhydroperoxide has been demonstrated. The factors complicating the production and isolation of the target product have been studied. As an alternative to 1,2,3,4-diepoxybutane, the synthesis of 1,2,4,5-diepoxypentane is proposed.
- Mel'nik,Nozhnin,Grechina,Kryukov,Yegorova,Danilova
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p. 455 - 459
(2007/10/03)
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- Regiocontrolled formation of iodohydrins and epoxides from Vic-diols
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A novel method for the stereoselective preparation of iodohydrins and epoxides from stereogenic vicinal diols is described. This new high-yield methodology consists of the conversion of thionocarbonates such as 12 to the primary iodo derivative 14 with complete regiocontrol. Deprotection of ther secondary alcohol derivative in 14 gives the corresponding synthetically versatile iodohydrin 16, which is converted to epoxide 17. This methodology has been applied to complex tetraols 29 and 34. In the case of diols the transformation is conveniently carried out in high yield as a one-pot reaction.
- Adiyaman,Khanapure,Hwang,Rokach
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p. 7367 - 7370
(2007/10/02)
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- Transition metal promoted acetylene isomerisation reactions in organic synthesis: A synthesis of (+)-(4S,5S) - Muricatacin
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An acetylene-vinylidene rearrangement has been employed as a key step in the enantiospecific synthesis of (+)-(4S,5S) - muricatacin.
- Quayle,Rahman,Herbert
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p. 8087 - 8088
(2007/10/02)
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- Asymmetric Dihydroxylation of Primary Allylic Halides and a Concise Synthesis of (-)-Diepoxybutane
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The asymmetric dihydroxylation (AD) of primary allylic halides is described.Enantiomeric excesses range from 40 to 98percent.Subsequent base treatment gives epoxy alcohols in high yields.This strategy is further illustrated by the synthesis of (-)-diepoxybutane, an important C4-chiral building block.
- Vanhessche, Koen P. M.,Wang, Zhi-Min,Sharpless, K. Barry
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p. 3469 - 3472
(2007/10/02)
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- A NEW APPROACH TO THE SYNTHESIS OF (-)-2,3-O-ISOPROPYLIDENE-2,3-DIHYDROXY-1,4-BIS(DIPHENYLPHOSPHINO)BUTANE(DIOP)
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(-)-2,3-O-Isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane (DIOP) has been prepared by reaction of (-)-1,2:3,4-diepoxybutane with lithium diphenylphosphide followed by ketalisation with 2,2-dimethoxypropane.
- Zhang, San-qi,Zhang, Sheng-yong,Feng, Rui
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p. 173 - 174
(2007/10/02)
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- Synthesis of chiral nonracemic diols via nucleophilic opening of (S,S)-1,2,3,4-diepoxybutane
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(S,S)-1,2,3,4-diepoxybutane was synthesized from (R,R)-dimethyl tartrate. Nucleophilic opening of this diepoxybutane gave a convenient method for generating a variety of chiral nonracemic diols.
- Devine, Paul N.,Oh, Taeboem
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p. 883 - 886
(2007/10/02)
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- An Experimental Study of the Reactions CH3CHO + Cl, C2H4O + Cl, and C2H4O + F in the Gas-Phase
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The reactions of chlorine and fluorine atoms with the structural isomers CH3CHO and C2H4O have been studied at low pressures and room temperature by the discharge flow technique with mass spectrometric detection.Using the reference reactions C2H6 + Cl --> C2H5 + HCl (0) C2H6 + F --> C2H5 + HF (00) the relative rate constant for the reactions CH3CHO + Cl --> products (1) C2H4O + Cl --> products (2) C2H4O + F --> products (3) were determined: k1/k0 = 1.04 +/- 0.09, k2/k0 = 0.49 +/- 0.04, k3/k00 = 0.47 +/- 0.05. - Reaction (1) proceeds mainly via hydrogen abstraction from the aldehyde group (>93percent) forming CH3CO.In the reactions of ethylene oxide (2), (3) the abstraction route is observed, contributions from addition channels in reaction (2) are discussed. - Keywords: Chemical Kinetics / Elementary Reactions / Mass Spectrometry / Radicals
- Bartels, M.,Hoyermann, K.,Lange, U.
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p. 423 - 427
(2007/10/02)
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