- Distannoxane speciation during esterification catalysis: Revealing insights provided by electrospray ionization mass spectrometry
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Dimeric tetraalkyldistannoxanes are have been reported to catalyze esterification reactions, but are difficult to investigate in detail due to the lack of suitable spectroscopic handles. Electrospray ionization mass spectrometry (ESI-MS), in conjunction with a tethered charge on a tin atom, reveals that immediate decomposition to mono-tin carboxylate compounds occurs in the presence of carboxylic acid.
- Crawford, Evan,Lohr, Tracy,Leitao, Erin M.,Kwok, Samantha,McIndoe, J. Scott
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Read Online
- Spirocyclic Cyclohexane Compounds
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Spirocyclic cyclohexane compounds corresponding to formula I In which R1, R2, R3 and R5 through R10 and X have defined meanings, a process for their preparation, pharmaceutical compositions containing such compounds, and the use of such spirocyclic cyclohexane compounds in the treatment and/or inhibition of pain and other conditions mediated by the ORL-1 or the ?-opioid receptor.
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Page/Page column 11
(2010/03/31)
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- Synthesis of spiro[4.5]decane CF-ring analogues of 1α,25- dihydroxyvitamin D3
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(Chemical Equation Presented) A novel series of analogues of calcitriol (1) is developed featuring a spirocyclic central core resulting from C18/C21-connection and C15/ C16-deletion (2a, 2b). The synthesis of the key intermediate involves an Eschenmoser r
- Schepens, Wim,Van Haver, Dirk,Vandewalle, Maurits,Bouillon, Roger,Verstuyf, Annemieke,De Clercq, Pierre J.
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p. 4247 - 4250
(2007/10/03)
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- PROCESS FOR THE SYNTHESIS AND PURIFICATION OF (4-METHOXYBUTYL) (4-TRIFLUOROMETHYLPHENYL)METHANONE
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A new process for the preparation of 4-trifluoromethylvalerophenone is described. The process described is a three step process comprising the synthesis of organomagnesium specie, coupling reaction between the of organomagnesiurn specie and trifluoromethylbenzonitrile or trifluoromethylbenzoyl chloride and preferably a purification of the product obtained in suitable reaction conditions. In the process an extraction phase of the final product is not required.
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Page/Page column 11
(2008/06/13)
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- 2-ALKOXYALKYL-2-ADAMANTYL (METH)ACRYLATE AND METHOD FOR PREPARING SAME
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2-Alkoxyalkyl-2-adamantyl (meth)acrylate and a method for preparing same are provided.
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- EFFICIENT AND/OR SELECTIVE METHYLATION BY DIAZOMETHANE OF ALCOHOLS, HALO ALCOHOLS, GLYCOLS, AMINO ALCOHOLS AND MERCAPTO ALCOHOLS WITH THE USE OF A PROTON-EXCHANGED X-TYPE ZEOLITE AS AN ACID-BASE BIFUNCTIONAL CATALYST
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Reactions of diazomethane with butanol, allyl alcohol and β- and γ-halo alcohols led to efficient methylation (giving the corresponding methyl ethers) with the use of a proton-excahnged X-type zeolite compared with H2SO4.The reactions with propylene and isobutylene glycols using the zeolite provided regioselective methylation of the primary OH rather than the secondary or tertiary OH, whereas regioselectivity was not observed in the reactions using H2SO4.The reactions with 2-aminoethanol and 2-mercaptoethanol showed high chemoselective S-methylation and N-monomethylation, respectively, in the presence of the zeolite instead of H2SO4.The mechanism for the reactions is proposed to involve acid-base bifunctional catalysis of the zeolite in which the acidic site reacts with diazomethane to form its conjugate acid, and the nucleophilicity of OH and SH groups is enhanced by the interaction of the basic site with the proton of the groups.
- Takeuchi, Hiroshi,Kishioka, Hiroaki,Kitajima, Kunio
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p. 121 - 126
(2007/10/02)
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- Ring-Opening Reactions. The Reactivity of Pyrrolidinium and Piperidinium Ions in Solution
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In this paper we report data on the reactivity of 1-phenyl-pyrrolidinium an -piperidinium iodides, and indolinium and tetrahydroquinolinium iodides, with MeO- in methanol and compare them with the corresponding 1,1-dimethylazoniacycloalkane iodides.
- Cerichelli, Giorgio,Luchetti, Luciana
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p. 10733 - 10738
(2007/10/02)
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- ON THE MECHANISM OF SELECTIVE CHLORINATION OF ETHERS WITH SULFURYL CHLORIDE IN THE DARK
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Alkyl 4-chlorobutyl ethers reacted in the dark with an excess of sulfuryl chloride at 70-85 deg C (bath) to afford α,β,β-trichlorinated ethers.The reactions were accelerated 3- to 6-fold by N,N-dimethyloctylammonium salts (0,12 to 1 mmol/mol ether).This catalyst promoted decomposition of sulfuryl chloride to chlorine and sulfur dioxide and thereby caused serious loss of sulfuryl chloride.The proportions of chlorination at α or α1 position were identical in the catalyzed or uncatalyzed version and depended on inductive effects, correlating well with Taft's linear free energy relationship log k/kref=ρ*?* for R = H, Me, Et, Pr in RCH2O(CH2)4Cl with ρ* = -2.6 +/- 0.1.The overall reactivity of ethers appears to vary like the nucleophilicity of the ether oxygen.It is concluded that hydride abstraction occurs indirectly, probably involving a chloroxonium ion pair.
- Buyck, Laurent De,Pooter, Herman De
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p. 807 - 816
(2007/10/02)
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- Molecular dynamics of 1-decanol in solution studied by NMR copled relaxation and stochastic dynamic simulations
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The 13C labeled 1-decanols at positions 1, 5 and 9 have been synthesized their dynamics in (CD3O-CD2CD2)2O, CD3CD2OD, and CD2Cl2 solvents have been studied by 13C-coupled relaxation methods. The expriments were performed oin the temperature range of 245-298 K. The data were fitted using the Redfield theory of nuclear relaxation to yield dipolar spectral densities to which transformed into Cartesian correlation times. The Cartesian correlation times obtained experimentally have a strong bearing on local anisotropic motion and suggest that the size of groups attached to a given carbon and also hydrogen bonding between 1-decanol and the various solvant moleculars have a profund effect on local segmenat motion. The hydrogn bond anchoring effect is apparently strongest near the hydrogen bonding site. The effect of solvant viscoleastic response, hydrogen bonding, and torsional forcs on the motion of Cartesian modes at different locations and end-to-end vectors in l-decanol are analyzed using both generalized (GLE) and ordinary Langevin equations (OLE) simulations. The asymmetry of Cartesian correlation as one moves away from the cahin center aries from the in the torsional potentials of the C-C-C-OH and C-C-C-C linkages at each end from a hydrogen bond anchoring effect at the first (C1). The stronger retardation effect at C1 observed in ethanol is found fom the GLE simulations to be mainly attributable to a large spatial blockage of the motion of the beads near-OH. For a by solute molcules with surrounded by solvent molecules with internal rotation, its motion is closely correlated with the solvent relaxation rate giving significantly reduced friction forces. Conversely, the local Cartesian relaxation for I-decanol in methylene choloride fails to correlate effectively with solvent relaxation and can be described satusfactorily by OLEs with δ-memory kernel. The contributions from overall tumbling and internal motion to the relaxation of local Cartesian modes and to the end-to-end vectors are analyzed by using calculated apparent activation energies.
- Liu, Fang,Horton,Mayne, Charles L.,Xiang, Tian-Xiang,Grant, David M.
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p. 5281 - 5294
(2007/10/02)
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- Tetrahydropyridine oxime compounds
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Certain N-substituted 1-(1,2,3,6-tetrahydro-3-pyridinyl)oximes and N-substituted 1-(1,2,3,6-tetrahydro-4-pyridinyl)oximes are useful as sigma binding agents for the treatment of depression, psychoses and/or inflammatory diseases.
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- The Elimination Kinetics of Methoxyalkyl Chlorides in the Gas Phase. Evidence for Neighboring Group Participation
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The rates of elimination of 3-methoxy-1-chloropropane and 4-methoxy-1-chlorobutane have been determined in a seasoned, static reaction vessel over the temperature range of 410-490 deg C and the pressure range of 56-181 torr.The reactions are homogeneous and unimolecular, follow a first-order rate low, and are invariant to the presence of a twofold or greater excess of the radical chain inhibitor toluene.The overall rate coefficients are given by the following Arrhenius equations: for 3-methoxy-1-chloropropane, logk1(s-1)=(12.92+/-0.48)-(226.0+/-6.8) kJ mol-1(2.303RT)-1; for 4-methoxy-1-chlorobutane, logk1(s-1)=(12. 9+/-0.26)-(218.1+/-3.5) kJ mol-1(2.303RT)-1.The CH3O group in 4-methoxy-1-chlorobutane has been found to assist anchimerically the elimination reaction, where dehydrochlorination and tetrahydrofuran formation arise from an intimate ion pair type of mechanism.The partial rates for these parallel eliminations have been determined and reported.Participation of the CH3O in 3-methoxy-1-chloropropane is barely detected.The present results give further evidence of intimate ion pair mechanism through neighboring group perticipation in the gas-phase elimination of certain types of organic molecules.
- Chuchani, Gabriel,Martin, Ignacio
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p. 431 - 433
(2007/10/02)
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