- Domino Methylenation/Hydrogenation of Aldehydes and Ketones by Combining Matsubara's Reagent and Wilkinson's Catalyst
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The methylenation/hydrogenation cascade reaction of aldehydes or ketones through a domino process involving two ensuing steps in a single pot is realized. The compatibility of Matsubara's reagent and Wilkinson's complex give a combination that allows, under dihydrogen, the transformation of a carbonyl function into a methyl group. This new method is suitable to introduce an ethyl motif from aromatic and aliphatic aldehydes with total chemoselectivity and total retention of α-stereochemical purity. The developed procedure is also extended to the introduction of methyl groups from ketones.
- Maazaoui, Radhouan,Pin-Nó, María,Gervais, Kevin,Abderrahim, Raoudha,Ferreira, Franck,Perez-Luna, Alejandro,Chemla, Fabrice,Jackowski, Olivier
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supporting information
p. 5732 - 5737
(2016/12/14)
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- Thermochemical study of the liquid phase equilibrium reaction of dihalomethanes by NMR spectroscopy
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The liquid phase equilibrium reaction of dihalomethanes (2CH2BrI ? CH2Br2 + CH2I2) has been investigated by NMR spectroscopy, as a function of the temperature and initial concentration of the reactants. The equilibrium constants have been experimentally determined for this reaction from the profile of the NMR spectra. Heat capacity measurements were carried out in the temperature range from 293.15 to 353.15 K by differential scanning calorimetry. The results relate the heats of formation of the three compounds and confirm the recently determined heat of formation of CH2I2 of 107.5 kJ mol-1.
- Dávalos,Lago,Baer, Tomas
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p. 230 - 234
(2007/10/03)
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- Transformation of aldehydes into (E)-1-alkenylsilanes and (E)-1-alkenylboronic esters with a catalytic amount of a chromium salt
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(Diiodomethyl)trimethylsilane (Me3SiCHI2, 1) is produced by treatment of iodoform with manganese in the presence of Me 3SiCl. Aldehydes are converted to (E)-1-trimethylsilyl-1-alkenes in a stereoselective manner with a geminal dichromium reagent generated from 1, manganese, Me3SiCl, and a catalytic amount of CrCl 3[thf]3 in THF. Similarly, (E)-1-alkenylboronic esters are prepared stereoselectively in good to excellent yields by treatment of aldehydes with a geminal dichromium reagent derived from Cl2CHB(OR) 2 [(OR)2 = OCMe2CMe2O] and LiI instead of 1.
- Takai, Kazuhiko,Kunisada, Yuji,Tachibana, Yukiko,Yamaji, Nana,Nakatani, Emi
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p. 1581 - 1586
(2007/10/03)
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- Quinuclidine compounds and drugs containing the same as the active ingredient
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The present invention provides an excellent squalene synthesizing enzyme inhibitor. Specifically, it provides a compound (I) represented by the following formula, a salt thereof or a hydrate of them. In which R1 represents (1) hydrogen atom or (2) hydroxyl group; HAr represents an aromatic heterocycle which may be substituted with 1 to 3 groups; Ar represents an optionally substituted aromatic ring; W represents a chain represented by (1) —CH2—CH2— which may be substituted, (2) —CH=CH— which may be substituted, (3) —C≡C—, (4) —NH—CO—, (5) —CO—NH—, (6) —NH—CH2—, (7) —CH2—NH—, (8) —CH2—CO—, (9) —CO—CH2—, (10) —NH—S(O)l—, (11) —S(O)l—NH—, (12) —CH2—S(O)— or (13) —S(O)l—CH2— (l denotes 0, 1 or 2); and X represents a chain represented by (1) a single bond, (2) an optionally substituted C1-6 alkylene chain, (3) an optionally substituted C2-6 alkenylene chain, (4) an optionally substituted C2-6 alkynylene chain, (5) a formula —Q— (wherein Q represents oxygen atom, sulfur atom, CO or N(R2) (wherein R2 represents a C1-6 alkyl group or a C1-6 alkoxy group)), (6) —NH—CO—, (7) —CO—NH—, (8) —NH—CH2—, (9) —CH2—NH—, (10) —CH2—CO—, (11) —CO—CH2—, (12) —NH—S(O)m—, (13) —S(O)m—NH—, (14) —CH2—S(O)m—, (15) —S(O)m—CH2— (wherein m denotes 0, 1 or 2) or (16) —(CH2)n—O— (wherein n denotes an integer from 1 to 6).
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- Determination, synthesis and survey of iodinated trihalomethanes in water treatment processes
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Trihalomethanes (THMs) are formed as a result of the interaction of free aqueous chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated, brominated and chlorobromotrihalomethanes are the most common disinfection by-products reported, iodinated trihalomethanes (ITHMs) can be formed when iodide is present in raw water. ITHMs have been usually associated with several medicinal or pharmaceutical taste and odor events in drinking water. For instance, the odor and taste threshold concentrations of iodoform are 0.02 and 5 μg/l, respectively. Different analytical techniques have been studied to identify these compounds but their quantitative determination has not been performed due to the lack of commercial standards. In this study ITHMs (CHCl2I, CHClI2, CHBr2I, CHBrI2 and CHBrClI) have been synthesized in order to evaluate headspace (HS), purge and trap (P&T), closed loop stripping analysis (CLSA) and liquid-liquid extraction (LLE) as analytical methods for determination. HS and LLE were followed by gas chromatography and electron capture detector (GC/ECD); whereas P&T and CLSA with gas chromatography and mass spectrometry (GC/MS). The most appropriate method, LLE/GC/ECD, was applied to evaluate the stability of ITHMs in water (ultrapure, raw and treated water) in order to confirm their presence in tap water. Ascorbic acid was the quenching reagent chosen to avoid free chlorine at the time of sample collection. Finally, samples from the different stages of the treatment plant in Barcelona (NE Spain) were analyzed. Only three (CHCl2I, CHBrClI and CHBr2I) of the six ITHMs were identified and determined, at average levels lower than 1μg/l, in sand filtered and ozonated waters. No ITHMs were identified in distribution system water. Trihalomethanes (THMs) are formed as a result of the interaction of free aqueous chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated, brominated and chlorobromotrihalomethanes are the most common disinfection by-products reported, iodinated trihalomethanes (ITHMs) can be formed when iodide is present in raw water. ITHMs have been usually associated with several medicinal or pharmaceutical taste and odor events in drinking water. For instance, the odor and taste threshold concentrations of iodoform are 0.02 and 5 μg/l, respectively. Different analytical techniques have been studied to identify these compounds but their quantitative determination has not been performed due to the lack of commercial standards. In this study ITHMs (CHCl2I, CHClI2, CHBr2I, CHBrI2 and CHBrClI) have been synthesized in order to evaluate headspace (HS), purge and trap (P and T), closed loop stripping analysis (CLSA) and liquid-liquid extraction (LLE) as analytical methods for determination. HS and LLE were followed by gas chromatography and electron capture detector (GC/ECD); whereas P and T and CLSA with gas chromatography and mass spectrometry (GC/MS). The most appropriate method, LLE/GC/ECD, was applied to evaluate the stability of ITHMs in water (ultrapure, raw and treated water) in order to confirm their presence in tap water. Ascorbic acid was the quenching reagent chosen to avoid free chlorine at the time of sample collection. Finally, samples from the different stages of the treatment plant in Barcelona (NE Spain) were analyzed. Only three (CHCl2I, CHBrClI and CHBr2I) of the six ITHMs were identified and determined, at average levels lower than 1μg/l, in sand filtered and ozonated waters. No ITHMs were identified in distribution system water. (C) 2000 Elsevier Science Ltd.
- Cancho, Beatriz,Ventura, Francesc,Galceran, Materesa,Diaz, Alfredo,Ricart, Susagna
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p. 3380 - 3390
(2007/10/03)
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- Photoproduct Characterization and Dynamics in the 248 nm Photlysis of CH3I Thin Films on Ag(111)
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The 248 nm photochemistry of methyl iodide thin films was studied using reflection absorption infrared spectroscopy (RAIRS), temperature programmed desorption (TPD), and time-of-flight quadrupole mass spectrometry (TOF-QMS).The formation of predominantly CH2I2 and CH4 and some C2H6, CH3CH2I, CHI3 and I2 photoproducts retained in the film was characterized by RAIRS and TPD.The integrated areas of the IR absorption bands for the two major photoproducts, CH2I2 and CH4, increase to a maximum and then decrease as photolysis of the film proceeds.A cross section for the loss of CH3I by 248 nm photolysis of the film was measured to be (1.0+/-0.1)E-19 cm2, approximately 1 order of magnitude lower than the gas-phase cross section.At all laser fluences used in this study, CH3, I, and CH3I were ejected into the gas phase.The CH3 TOF distribution showed the signature of the gas-phase CH3I photodissociation dynamics-two sharp peaks corresponding to the production of iodine atoms in the I(2P3/2) and I*(2P1/2) states.The TOF distributions of I and CH3I were fit by Maxwell-Boltzmann distributions corresponding to temperatures of 1400 and 1170 K, respectively.Three other species-CH4, I2 and CH2I2-were observed in TOF-QMS, but only at higher laser fluences.It was determined that the I2 and CH2I2 species are most likely fragments of a larger molecule, perhaps a cluster species, that photodesorbs as the film becomes enriched with photoproducts.The mechanism for CH4 photoejection appears to be of a different nature.The photochemistry of methyl iodide thin films can be understood in terms of a combination of photoproceses occuring in the film and at the film surface.
- Coon, S. R.,Myli, K. B.,Grassian, V. H.
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p. 16416 - 16424
(2007/10/02)
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- Formation of Radical Cations of Polyiodomethanes: A Pulse Radiolysis Study
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The transient optical absorption band (λmax = 380nm, t1/2 = 23μs and ε = 2010dm3 mol-1 cm-1) produced on pulse radiolysis of N2O-saturated aqueous solution of CH2I2 (pH 6.0) has been assigned to the OH adduct radical, CH2I2*OH.In acidic aqueous solutions, CH2I2+ (λmax = 380 and 570nm, t1/2 = 3μs and ε570 = 2150dm3 mol-1 cm-1) has been identified as the intermediate.The rate constants for the reaction of OH radicals with CH2I2 to form CH2I2*OH and CH2I2+ have been determined to be 2.1*109 and 6.0*109 dm3 mol-1 s-1 respectively.Cl2- has been found to oxidize CH2I2 to CH2I2+ with a bimolecular rate constant of 1.7*108 dm3 mol-1 s-1.CH2I2+ is a good oxidant and oxidizes I-, Br-, and methyl disulphide with high rate constants close to the diffusion limit.I2 is the main stable end product formed on γ-radiolysis and its yield is equal to 1/2G(-CH2I2).The transient optical absorption bands observed on pulse radiolysis of CH2I2 and CHI3 in 1,2-dichloroethane have been assigned to CH2I2+ (λmax = 380 and 590nm) and CHI3+ (λmax = 400 and 610nm).
- Mohan, Hari,Moorthy, Pervaje N.
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p. 277 - 282
(2007/10/02)
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- Studies on the Synthesis of Heterocyclic Compounds. XVI. Cleavage of 1,3-Benzodioxoles and -Benzoxathioles by Sodium Iodide-Acyl Chloride
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The cleavage reaction of ethereal and thioethereal bonds with sodium iodide and acyl chloride has been studied.In all the 1,3-benzodioxoles and -benzoxathioles studied, the opening of the heterocyclic ring with formation of 1,2-diacetoxybenzene or 2-hydroxythiophenol diacetic acid ester and gem-diiodoalkanes and iodoalkenes has been observed.The structure of newly prepared compounds has been determined by analytical and spectroscopic data or comparison with authentic samples.
- Corda, Luciana,Fadda, Anna Maria,Maccioni, Antonio,Maccioni, Anna Maria,Podda, Gianni
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p. 311 - 314
(2007/10/02)
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- High-Field NMR Determination of Magnetic Susceptibility Tensors and Angular Correlation Factors of Halomethanes
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Quadropolar splittings in the high resolution deuteron spectra of deuterated haloforms (CX3(2)H, X=Cl, Br, I) and methylene halides (CX2H(2)H) have been measured at 14.35 T (93.5 MHz) and used to determine the anisotropy or asymmetry of their molecular magnetic susceptibility tensors.By combination with the known isotropic susceptibilities, the principal susceptibility tensors have been deduced and decomposed into bond susceptibility tensors.Neither the average susceptibilities nor the principal susceptibility tensor elements of the complete halomethane series follow Pascal's additivity rules.The phenomenon is tentatively attributed to a variable paramagnetic contribution perpendicular to the X-bond.Angular correlation Kirkwood g2 factors have been determined for CHCl3 and CHBr3 and are compared with available literature data.
- Bothner-By, A. A.,Dadok, J.,Mishra, P. K.,Zijl, P. C. M. Van
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p. 4180 - 4184
(2007/10/02)
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- Organic compounds and process
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The present invention provides a novel process for preparing known prostaglandins, particularly 9-deoxo-9-methylene-16,16-dimethyl-PGE2. This well known and useful prostaglandin is prepared from D-glucose through a series of efficient reactions. Also provided are novel intermediates which are useful for preparation of a wide variety of prostaglandins.
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- BIOSYNTHESIS OF PODOPHYLLUM LIGNANS - I. CINNAMIC ACID PRECURSORS OF PODOPHYLLOTOXIN IN PODOPHYLLUM HEXANDRUM
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Feeding experiments in Podophyllum hexandrum plants have established that phenylalanine, cinnamic acid and ferulic acid are good precursors of the two major aryltetralin lignans podophyllotoxin and 4'-demethylpodophyllotoxin.Sinapic and 3,4,5-trimethoxycinnamic acids were poorly utilized, showing that the substitution pattern of the pendent aryl ring is built up after coupling of the two phenylpropane units.Degradation studies on podophyllotoxin derived from ferulic acid show that the two halves of the lignan molecule are equally labelled supporting a biosynthetic sequence involving oxidative coupling of two similar phenylpropane precursors having the substitution pattern of ferulic acid.Although 3,4-methylenedioxycinnamic acid was readily incorporated, degradative studies prove that this compound is not incorporated intact, but via a metabolic sequence in which the methylenedioxy carbon atom enters the C1-pool and then labels the methylenedioxy and methoxyl substituents of podophyllotoxin.The rest of the skeleton is incorporated via ferulic acid, presumably by way of caffeic acid.Key Word Index - Podophyllum hexandrum; Podophyllaceae; aryltetralin; lignans; biosynthesis; podophyllotoxin.
- Jackson, David E.,Dewick, Paul M.
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p. 1029 - 1036
(2007/10/02)
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- Catalytic Interconversion of Alkyl Halides by Gas-liquid Phase-transfer Catalysis
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High halogen exchange conversions are achieved when a gaseous mixture of alkyl halides (chlorides, bromides, iodides) is passed over a solid bed consisting of porous inorganic supports bearing a phase-transfer catalyst under gas-liquid phase-transfer catalysis (g.l.-p.t.c.) conditions.The process is catalytic since the bed undergoes no changes once it reaches operating conditions.For example, a methylene dichloride and bromoethane mixture is converted into all the halogen-exchange products, and their statistical distribution at equilibrium depends on the original ratio of the halogens in the organic reagents.Catalytic activity is high: 200 ml of such a mixture can be converted in 1 h by passage through 200 g of alumina coated with 10 percent tetrabutylphosphonium bromide.The catalytic process is promoted by the halide anions present as Q(1+)X(1-) in the liquid phase constituted by the molten catalyst and as Na(1+)X(1-) in the solid inorganic support; the halide anions partition themselves between the liquid and solid phases as a function of their respective affinities.This catalysis depends on the diffusion, partition, and adsorption of the alkyl halides between the gaseous, liquid, and solid phases, as well as on their intrinsic nucleophilic reactivity.Mechanistic aspects and industrial applicability are discussed.
- Tundo, Pietro,Venturello, Paolo,Angeletti, Enrico
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p. 485 - 492
(2007/10/02)
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- THE REACTIONS OF SOME 1,1,1-TRIBROMO-ALKYL SYSTEMS WITH THIOLATE ANIONS
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Compounds containing a 1,1,1-tribromoethyl group are normally dehydrobrominated by reaction with sodium thiolates.If a 1,1,1-tribromobut-3-ene fragment is present cyclisation to a 2,2-dibromocyclopropylmethyl thioether or rearrangement are also observed.
- Baird, Mark S.,Hoorfar, Alireza,Mitra, Manjushri
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p. 2509 - 2512
(2007/10/02)
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