- Mild conversion of alcohols to alkyl halides using halide-based ionic liquids at room temperature
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Formula presented Alcohols were efficiently converted to alkyl halides using 1-n-butyl-3-methylylimidazolium halides (ionic liquids) in the presence of Bronsted acids at room temperature. The alkyl halide products were easily isolated from the reaction mixture via simple decantation or extraction, and the 1-n-butyl-3-methylimidazolium cation could be recycled for further uses.
- Ren, Rex X.,Wu, Jeff Xin
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Read Online
- Convergent synthesis of a deuterium-labeled serine dipeptide lipid for analysis of biological samples
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Bacterial serine dipeptide lipids are known to promote inflammatory processes and are detected in human tissues associated with periodontal disease or atherosclerosis. Accurate quantification of bacterial serine lipid, specifically lipid 654 [((S)-15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, (3S)-l-serine] isolated from Porphyromonas gingivalis, in biological samples requires the preparation of a stable isotope internal standard for sample supplementation and subsequent mass spectrometric analysis. This report describes the convergent synthesis of a deuterium-substituted serine dipeptide lipid, which is an isotopically labeled homologue that represents a dominant form of serine dipeptide lipid recovered in bacteria.
- Dietz, Christopher,Clark, Robert B.,Nichols, Frank C.,Smith, Michael B.
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- STABILIZATION IN THE ORDER I>Br>Cl AMONG TRIMETHYLSILYLMETHYL HALIDES, COMPARED TO CARBON ANALOGS. POSSIBLE ROLE OF ELECTRONEGATIVITY IN ORGANOSILICON CHEMISTRY
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Electronegativities may be used to rationalize the observation that the equilibrium, CH3(CH2)3I + (CH3)3SiCH2Cl CH3(CH2)3Cl + (CH3)3SiCH2I, lies to the right.
- Peterson, Paul E.
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- Tributylarsonium-2,2,3,3,4,4-hexafluorocyclobutane Ylide. Preparation and Cleavage
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F-cyclobutane forms a stable ylide with n-tributylarsine.In contrast to the halogen cleavage of the analogous phophonium ylide, which gives 1,1-dihaloalkanes, the arsonium ylide reacts with bromine and iodine to give the 1-halo-F-cyclobutenes.
- Burton, Donald J.,Valk, Paul D. Vander
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- A study of the lithiation of 2,6-dibromopyridine with butyllithium, and its application to synthesis of L-739,010
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Mono-lithiation of 2,6-dibromopyridine by n-BuLi is complicated by deprotonation of the pyridine ring by the resulting mono-lithium species. This problem can be eliminated by a reverse addition, but this causes formation of the undesired dilithio species. However, rapid lithium-halogen exchange between 2,6-dibromopyridine and 2,6-dilithiopyridine produces 2-bromo-6-lithiopyridine cleanly. Thus, using reverse addition, the mono-lithiated pyridine can be generated in 98% yield.
- Cai, Dongwei,Hughes, David L.,Verhoeven, Thomas R.
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- 1,3-Diphenyldisiloxane Enables Additive-Free Redox Recycling Reactions and Catalysis with Triphenylphosphine
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The recently reported chemoselective reduction of phosphine oxides with 1,3-diphenyldisiloxane (DPDS) has opened up the possibility of additive-free phosphine oxide reductions in catalytic systems. Herein we disclose the use of this new reducing agent as an enabler of phosphorus redox recycling in Wittig, Staudinger, and alcohol substitution reactions. DPDS was successfully utilized in ambient-temperature additive-free redox recycling variants of the Wittig olefination, Appel halogenation, and Staudinger reduction. Triphenylphosphine-promoted catalytic recycling reactions were also facilitated by DPDS. Additive-free triphenylphosphine-promoted catalytic Staudinger reductions could even be performed at ambient temperature due to the rapid nature of phosphinimine reduction, for which we characterized kinetic and thermodynamic parameters. These results demonstrate the utility of DPDS as an excellent reducing agent for the development of phosphorus redox recycling reactions.
- Buonomo, Joseph A.,Cole, Malcolm S.,Eiden, Carter G.,Aldrich, Courtney C.
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p. 3583 - 3594
(2020/09/15)
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- Method of preparing 1-bromobutane continuously
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The invention discloses a method of preparing 1-bromobutane continuously. 1-bromobutane is produced continuously by carrying out a reaction within a short time in a micro reactor without a catalyst bytaking normal butanol and hydrobromic acid as raw materials. Two strands of materials enter the micro reactor through a metering pump and are preheated, mixed and reacted to obtain a coarse product 1-bromobutane. Compared with the prior art, a catalyst sulfuric acid is not used, so that treatment of sulfuric acid at the back end is reduced, the separation process is simplified, the environmentalpollution is reduced, the utilization ratio of hydrobromic acid is high, the conversion rate of reactants is high, and the selectivity and yield of a target product are relatively high and the like. The method is simple and safe to operate, can be used for producing 1-bromobutane continuously with a high yield, and has a good industrial application prospect.
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Paragraph 0037-0064
(2018/12/14)
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- An efficient conversion of alcohols to alkyl bromides using pyridinium based ionic liquids: A green alternative to appel reaction
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Pyridinium based ionic liquids namely 4-alkylpyridinium bromides were prepared and used for the conversion of alcohols to alkyl bromides in the presence of p-toluenesulphonic acid in the absence of volatile organic compounds. This solvent free procedure promises to be a much improved and environmentally benign alternative to the Appel reaction.
- Das, Pranab J.,Das, Jupitara,Das, Dimpee
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p. 651 - 654
(2018/02/09)
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- Why is cis/trans stereoinversion with Li+(THF)4 migration across the phenyl ring of α-lithiostyrene accelerated by two ortho-methyl groups?
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Common wisdom might anticipate that two methyl groups placed on a molecular migration route should act as an impediment. However, the “conducted tour” migration of Li+(THF)4 across the aryl ring (“π-route”) during the cis/trans stereoinversion of α-arylvinyllithiums had been found to occur with practically equal velocities in the presence of either one or two ortho-alkyl substituents. We now report that the omission of both ortho-methyl groups retards the stereoinversion process. In order to arrive at an answer to the title question, we investigate the aggregation equilibria and microsolvation states of ortho, ortho′-unsubstituted α-lithiostyrenes by means of approved secondary NMR criteria. Beyond such necessary knowledge about the ground-state properties, we provide kinetic evidence showing that the retarded cis/trans stereoinversion of α-lithiostyrene proceeds by the pseudomonomolecular, ionic mechanism with Li+(THF)4 migration.
- Knorr, Rudolf,Lattke, Ernst,Ruhdorfer, Jakob,Ferchland, Kathrin,von Roman, Ulrich
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p. 1621 - 1631
(2018/02/28)
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- Facile continuous process for gas phase halogen exchange over supported alkyl phosphonium salts
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Chloride-bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.
- Sharma, Priti,Sasson, Yoel
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p. 2824 - 2828
(2018/02/06)
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- Sulfonyl halide synthesis by thiol oxyhalogenation using NBS/NCS – iPrOH
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A rapid and facile method provides a general route to sulfonyl bromides/chlorides by the oxidation of thiols using NXS – ROH (X?=?Br,Cl, R?=?iPr) as an oxyhalogenation reagent. Control experiments suggest that the alcohol component is the source of oxygen. The proposed method enable the access to structurally diverse sulfonyl bromides and chlorides including challenging examples, inaccessible by other synthetic methods.
- Silva-Cuevas, Carolina,Perez-Arrieta, Carlos,Polindara-García, Luis A.,Lujan-Montelongo, J. Armando
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p. 2244 - 2247
(2017/05/16)
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- Unexpected distinction in reactivity of pentafluorobenzenesulfonyl halides toward organolithiums and organomagnesium halides
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C6F5SO2Cl reacts with organolithiums and organomagnesium halides RM (R = Me, Bu, Ph; M = Li, MgX) to give mainly C6F5H and C6F5Cl. C6F5SO2Br and
- Bardin, Vadim V.,Maksimov, Alexander M.
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p. 731 - 737
(2017/10/16)
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- Selective Cobalt-Catalyzed Reduction of Terminal Alkenes and Alkynes Using (EtO)2Si(Me)H as a Stoichiometric Reductant
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While attempting to effect Co-catalyzed hydrosilylation of β-vinyl trimethylsilyl enol ethers, we discovered that, depending on the silane, solvent, and the method of generation of the reduced cobalt catalyst, a highly efficient and selective reduction or hydrosilylation of an alkene can be achieved. This paper deals with this reduction reaction, which has not been reported before in spite of the huge research activity in this area. The reaction, which uses the air-stable [2,6-bis(aryliminoyl)pyridine)]CoCl2 activated by 2 equiv of NaEt3BH as the catalyst (0.001-0.05 equiv) and (EtO)2SiMeH as the hydrogen source, is best run at ambient temperature in toluene and is highly selective for the reduction of simple unsubstituted 1-alkenes and the terminal double bonds in 1,3- and 1,4-dienes, β-vinyl ketones, and silyloxy dienes. The reaction is tolerant of various functional groups such as bromide, alcohol, amine, carbonyl, di- or trisubstituted double bonds, and water. Highly selective reduction of a terminal alkyne to either an alkene or alkane can be accomplished by using stoichiometric amounts of the silane. Preliminary mechanistic studies indicate that the reaction is stoichiometric in the silane and both hydrogens in the product come from the silane.
- Raya, Balaram,Biswas, Souvagya,Rajanbabu
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p. 6318 - 6323
(2016/09/09)
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- Iron-catalyzed borylation of alkyl, allyl, and aryl halides: Isolation of an iron(I) boryl complex
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Activation of B2pin2 with tBuLi facilitates the Fe-catalyzed borylation of alkyl, allyl, benzyl, and aryl halides via the formation of Li[B2pin2(tBu)] (1). The reaction of 1 with a representative iron phosphine precatalyst generates the unique iron(I) boryl complex [Fe(Bpin)(dpbz)2] (2).
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Gallagher, Timothy,Murphy, Damien M.,Pye, Dominic R.
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supporting information
p. 5940 - 5943
(2015/01/08)
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- Rhodium-cobalt bimetallic nanoparticles: A catalyst for selective hydrogenation of unsaturated carbon-carbon bonds with hydrous hydrazine
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Our studies on the effect of metal compositions on the catalytic activity of the rhodium-based bimetallic nanocatalysts revealed that the nanoparticles with a 4:1 ratio of rhodium to cobalt, were more active than the rhodium monometallic nanoparticles in the selective hydrogenation of unsaturated carbon-carbon bonds with hydrous hydrazine as a hydrogen source. The nanocatalysts effected this hydrogenation process in good-to-excellent yields with high functional group tolerance, and could be reused 10 times without the loss of catalytic activity. The catalyst characterization by X-ray photoelectron spectroscopy, transmission electron microscopy and line-scanning analysis suggested that the coexistence of metallic rhodium and cobalt plays an important role in the enhancement of catalytic activity. Copyright
- Lin, Jin,Chen, Jing,Su, Weiping
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supporting information
p. 41 - 46
(2013/03/14)
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- donor-acceptor oligogermanes: Synthesis, structure, and electronic properties
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A series of oligogermanes, (Me3Si)3GeGeCl 3, (C6F5)3GeGePh3, (C6F5)3GeGe(p-Tol)3, and (C 6F5)2Ge[Ge(p-Tol)3]2, containing substituents with different electronic properties at neighboring germanium atoms were synthesized. According to X-ray diffraction studies, UV/visible spectroscopy, and quantum chemical calculations, these donor-acceptor oligogermanes are characterized by energies of electronic transitions lower than those for other similar compounds.
- Zaitsev, Kirill V.,Kapranov, Andrey A.,Churakov, Andrei V.,Poleshchuk, Oleg Kh.,Oprunenko, Yuri F.,Tarasevich, Boris N.,Zaitseva, Galina S.,Karlov, Sergey S.
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p. 6500 - 6510
(2013/12/04)
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- Synthesis of silica bromide as heterogeneous reagent and its application to conversion of alcohols to alkyl bromides
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Silica bromide as heterogeneous reagent is prepared from the reaction of silica gel with PBr3 as a nonhydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that the silica bromide is a suitable and efficient reagent for conversion of alcohols to alkyl bromides under mild conditions at room temperature. The easy availability of this reagent makes this simple procedure attractive and a practical alternative to the existing methods.
- Mohanazadeh, Farajollah,Sedrpoushan, Alireza,Zolfigol, Mohammad A.,Veisi, Hojat
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p. 598 - 603,6
(2012/12/11)
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- Reactions of perfluorinated alkenyl-, alkynyl-, alkyltrifluoroborates, and selected hydrocarbon analogues with the halogenating agents Hal2 (Hal = F, Cl, Br), "brF" (BrF3-Br2 1:1), and ICl
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Reactions of [Bu4N][RBF3] [R = CnF 2n+1CF=CF (cis, trans), CF2=CF, CF2=C(CF 3), trans-C4H9CF=CF, trans-C6H 5CF=CF, C4H9CH=CH (cis, trans), CF 3C≡C, and C4H9C≡C] with chlorine, bromine, BrF3 + Br2 (as equivalent of "BrF"), and ICl in solution (CH2Cl2, CHCl3, CF 3CH2CF2CH3) led to 1, 2-addition of halogen and/or replacement of boron by halogen (halodeboration). The reaction of [Bu4N][CF3C≡CBF3] with less than equimolar amounts of diluted fluorine (5 %) in 1, 1, 1, 3, 3-pentafluorobutane (PFB) showed only [Bu4N][CF3CF2CF 2BF3] as fluorine addition product besides extensive fluorodeboration. Suspensions of the insoluble K[CF2=CFBF 3] salt reacted with Cl2 and Br2 in CH 2Cl2 giving preferentially products of halogen addition across the C=C bond. In reactions with ICl iododeboration with formation of CF2=CFI occurred besides 1, 2-addition with formation of [CF 2I-CFClBF3]-. The halodeboration reaction of[Bu4N][trans-C4H9CF=CFBF3] with Br2, "BrF", and ICl, of K[trans-C6H 5CF=CFBF3] with Br2, and of [Bu 4N][trans-C4F9CF=CFBF3] with ICl proceeded stereospecifically. Copyright
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
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experimental part
p. 565 - 579
(2012/05/20)
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- Iron-copper cooperative catalysis in the reactions of alkyl grignard reagents: Exchange reaction with alkenes and carbometalation of alkynes
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Iron-copper cooperative catalysis is shown to be effective for an alkene-Grignard exchange reaction and alkylmagnesiation of alkynes. The Grignard exchange between terminal alkenes (RCH=CH2) and cyclopentylmagnesium bromide was catalyzed by FeCl3 (2.5 mol %) and CuBr (5 mol %) in combination with PBu3 (10 mol %) to give RCH2CH 2MgBr in high yields. 1-Alkyl Grignard reagents add to alkynes in the presence of a catalyst system consisting of Fe(acac)3, CuBr, PBu3, and N,N,N″,N″-tetramethylethylenediamine to give β-alkylvinyl Grignard reagents. The exchange reaction and carbometalation take place on iron, whereas copper assists with the exchange of organic groups between organoiron and organomagnesium species through transmetalation with these species. Sequential reactions consisting of the alkene-Grignard exchange and the alkylmagnesiation of alkynes were successfully conducted by adding an alkyne to a mixture of the first reaction. Isomerization of Grignard reagents from 2-alkyl to 1-alkyl catalyzed by Fe-Cu also is applicable as the first 1-alkyl Grignard formation step.
- Shirakawa, Eiji,Ikeda, Daiji,Masui, Seiji,Yoshida, Masatoshi,Hayashi, Tamio
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scheme or table
p. 272 - 279
(2012/03/07)
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- Mechanistic investigation of oxidation of some substituted aromatic acetals with N-bromosuccinimide in acetonitrile medium - A kinetic approach
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The oxidation of meta- and para-substituted aromatic acetals by N-bromosuccinimide (NBS) to the corresponding esters and alkyl bromide, is first-order in [NBS] and [acetal]. The effect of substituents in the aromatic ring of some aromatic acetals [X-C6H4CH(OBu-B) 2] {X = H, p-OMe, p-Me, p-Cl, p-NO2, m-OMe, m-CI, m-NO2} on the kinetics of above oxidation has been studied in acetonitrile medium at various temperatures by iodometric method. The rate of the reaction increases with the increase in the dielectric constant of the medium. The stoichiometry of the reaction is found to be 1 : 1. A primary kinetic isotopic effect kH/kD of 1.8 is observed, which indicates the C-H bond cleavage of the aldehydic carbon in the rate determining step. The Hammett reaction constant (a) for the reaction is found to be -1.38 and -1.42 at 313 K and 323 K respectively. The Exner plot is found to be linear with the isokinetic temperature 132 K. The kinetic and activation parameters Ea, A, ΔH≠, ΔG≠ and ΔS≠ have been calculated. A mechanism involving simultaneous loss of H+ from the aldehydic carbon and expulsion of bromide ion with the formation of carbonium ion intermediate is proposed.
- Mathiyalagan
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p. 1499 - 1506
(2013/02/23)
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- Synthesis of an H3 antagonist via sequential one-pot additions of a magnesium ate complex and an amine to a 1,4-ketoester followed by carbonyl-directed fluoride addition
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We describe the development of an efficient and scalable process for the preparation of fluorocyclobutane-containing H3 antagonist, 1. The synthesis was accomplished by the chemoselective addition of a magnesium ate complex and an amine to a 1,4-ketoester in a one-pot sequence, followed by a diastereoselective carbonyl-directed fluorination. The chemoselective addition of the magnesium ate complex to the ketoester benefited from tight stoichiometric control, short addition times, and lower reaction temperatures, and thus was amenable to rapid mixing and excellent heat transfer in a flow reactor.
- Hawkins, Joel M.,Dube, Pascal,Maloney, Mark T.,Wei, Lulin,Ewing, Marcus,Chesnut, Stephen M.,Denette, Joshua R.,Lillie, Brett M.,Vaidyanathan, Rajappa
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p. 1393 - 1403
(2012/11/07)
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- Investigation of the stability of quaternary ammonium methyl carbonates
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Quaternary ammonium compounds are used commercially for a variety of applications and some are of interest as ionic liquids. For many years dimethyl carbonate has been touted as a green reagent, including its use for methylation (quaternization) of tertiary amines. In addition, substitution of the methyl carbonate by other anions can be efficiently and cleanly accomplished by reaction with the corresponding acid. How stable are these methyl carbonate quaternary compounds? High field 13C NMR shows that in the presence of water, the methyl carbonate is converted to bicarbonate. Headspace GCMS indicates that the alkylammonium methyl carbonate salts are stable below 170-180 °C while the bicarbonate salts are stable to only about 140 °C. Thermal decomposition occurs by decarboxylation and by dealkylation. AOCS 2011.
- Weisshaar, Duane E.,Earl, Gary W.,Amolins, Michael W.,Mickalowski, Kyle L.,Norberg, Justin G.,Rekken, Brian D.,Burgess, Angela M.,Kaemingk, Bethany D.,Behrens, Katherine C.
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body text
p. 199 - 205
(2012/06/16)
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- NOVEL SEMI-SYNTHETIC GLYCOPEPTIDES AS ANTIBACTERIAL AGENTS
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Semi-synthetic glycopeptides having antibacterial activity are described, in particular, the semi-synthetic glycopeptides described herein are made by chemical modification of the a glycopeptide (Compound A, Compound B, Compound H or Compound C) or the monosaccharide made by hydrolyzing the disaccharide moiety of the amino acid-4 of the parent glycopeptide in acidic medium to give the amino acid-4 monosaccharide; conversion of the monosaccharide to the amino-sugar derivative; acylation of the amino substituent on the amino acid-4 amino-substituted sugar moiety on these scaffolds with certain acyl groups; conversion of the amide group in amino acid-3 on these scaffolds to various acylamide, acylsulfonamide, acylsulfonylurea derivatives; aminomethylation with substituent containing sulfonamide or acylsulfonamide group on amino acid-7 through Mannich reaction; and conversion of the acid moiety on the macrocyclic ring of these scaffolds to certain substituted amides. Also provided are methods for the synthesis of the compounds, pharmaceutical compositions containing the compounds, and methods of use of the compounds for the treatment and/or prophylaxis of diseases, especially bacterial infections.
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- Alkylation of the ambident indole ion in ionic liquids
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Alkylation of the ambident indole anion in ionic liquids has been investigated. The reaction rate is greater in ionic liquids than in organic solvents. The polarity of certain ionic liquids has been determined to be located between methanol and acetonitrile. 2008 Springer Science+Business Media, Inc.
- Vavilina,Zicmanis,Drozdova,Mekss,Klavins
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p. 530 - 541
(2013/07/27)
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- Simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid
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A simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid (HI) is reported. The alkyl iodides were obtained in quick and easy work-up with good to excellent yields (66-94%) and very high purities (97-99%). Freshly prepared iodomethane and 1-iodobutane were applied to synthesize biologically relevant 3,7-dimethyladenine and 9-butyladenine, which were characterized thoroughly using 1D and 2D NMR, individually.
- Klein, Suzane M.,Zhang, Cungen,Jiang, Yu Lin
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p. 2638 - 2641
(2008/09/19)
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- Transformation of tertiary amines into alkylating reagents by treatment with 2-chloro-4,6-dimethoxy-1,3,5-triazine. A synthetic application of side-reaction accompanying coupling by means of 4-(4,6-dimethoxy-[1,3,5] triazin-2-yl)-4-methyl-morpholin-4-ium chloride (DMTMM)
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Mild reaction conditions are described for the preparation of a number of alkyl chlorides and 2-dialkyl(aryl)amino-4,6-dirnethoxy-1,3,5-triazines by dealkylation of quaternary triazinylammonium chlorides formed as reactive intermediates in reaction of tertiary amines with 2-chloro-4,6-dimethoxy-1,3,5- triazine. The high selectivity of substitution was observed within the reactivity order of the alkyl groups: benzyl ~ allyl > methyl > n-alkyl. Studies on dealkylation of S-(-)-J-dimethyl-(1-phenylethyl)amine to R-(+)-1-chloro-1-phenylethane revealed that reaction proceeded with an inversion of configuration on the carbon atom as may be expected for SN2 type substitution. The scope of reaction was extended by exchange of anion in quaternary triazinylammonium chlorides with 1-, SCN-, C6H5O-, CH3COO- followed by N-dealkylation step.
- Kolesinska,Kaminski
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experimental part
p. 2115 - 2123
(2009/04/07)
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- Synthesis and characterization of acetonitrile-ligated transition-metal complexes with tetrakis(pentafluorophenyl)borate as counteranions
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Complexes with the general formula [MII(NCCH3) 6][TPFB]2 [M = Cr, Fe, Co, Ni, Cu, Zn, (TPFB)- = tetrakis-(pentafluorophenyl)borate] were synthesized and characterized both in the solid state and in solution. According to the spectroscopic data, [TPFB] can be considered as a truly noncoordinating anion. The NCCH3 ligands are lost if the samples are kept at room temperature for extended periods of time. Thermolysis leads to the loss of the NCCH3 ligands and decomposition of the anion above 100°C with the formation of MF2. It has to be noted that distortion of the geometries of the CuII, ZnII and CrII complexes occurs, as evidenced by infrared spectroscopy. The complexes can be easily prepared and obtained in high yields and are moderately sensitive to air. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Hijazi, Ahmed K.,Hmaideen, Akef Al,Syukri, Syukri,Radhakrishnan, Narayanan,Herdtweck, Eberhardt,Voit, Brigitte,Kuehn, Fritz E.
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scheme or table
p. 2892 - 2898
(2009/03/11)
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- ORGANIC COMPOUNDS
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The invention related to a novel process, novel process steps and novel intermediates useful in the synthesis of pharmaceutically active compounds, especially renin inhibitors, such as Aliskiren. Inter alia, the invention relates to a process for the manufacture of a compound of the formula II, or a salt thereof, and a compound of formula Vl or a salt thereof, wherein R3 and R4 as well as Act are as defined in the specification, and processes of manufacturing these. Additionally transformation of compounds (Vl) with metallo organic compounds (VII) give rise to the new compounds (VMI) which are direct precursors for the preparation of Aliskiren.
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Page/Page column 68-69
(2010/11/27)
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- Cleavage of phosphate ester bonds by use of novel group 13 chelate compounds
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A novel chemical compound has a general formula (LX)nY wherein X is selected from a group consisting of a group 13 element other than boron, Y is selected from a group consisting of a halide, a chlorate, a sulfate and a nitrate and L is a chelating ligand containing two nitrogen and two oxygen donor groups where n=1 or 2.
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Page/Page column 9
(2008/06/13)
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- RXR modulators with improved pharmacologic profile
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The present invention provides a novel class of RXR modulator compounds that exhibit an improved pharmacologic profile relative to the profile of previously studied RXR modulators, including those that share common structural features with the presently claimed modulators. The present invention also provides synthetic methods for preparing these compounds as well as pharmaceutical compositions incorporating these novel compounds and methods for the therapeutic use of such compounds and pharmaceutical compositions.
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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- Synthesis of 2-γ-N-(aminoethyl)aminopropyl-2-methyl-6-alkyl(aryl,H)-1,3-dioxa-6- aza-2-silacyclooctanes
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Some new 2-γ-N-(aminoethyl)aminopropyl-2-methyl-1,3-dioxa-6-aza-2- silacyclooctane and 2-γ-N-(aminoethyl)aminopropyl-2-methyl-6-alkyl(aryl)-1,3-dioxa-6-aza- 2-silacyclooctanes have been synthesized from γ-chloropropyldimethoxymethyl silane by ethylenediamine substitution and diethanolamine or N-alkyl(aryl)diethanolamines substitution. The resulting silocanes have been characterized by elemental analyses, IR, and 1H NMR.
- Yang,Lin,Li
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p. 2817 - 2822
(2007/10/03)
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- A facile conversion of thiols to alkyl halides by triphenylphosphine/N-halosuccinimides
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Thiols are efficiently converted to alkyl halides in high to excellent yields when treated with triphenylphosphin/N-halosuccinimide (halogen: Br,Cl, and I) in dichloromethane at room temperature.
- Iranpoor,Firouzabadi,Aghapour
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p. 1176 - 1178
(2007/10/03)
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- (Chloro-phenylthio-methylene)dimethylammonium chloride (CPMA) an efficient reagent for selective chlorination and bromination of primary alcohols
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(Chloro-phenylthio-methylene)dimethylammonium chloride reacts smoothly with a variety of alcohols, to afford the corresponding alkyl chloride in good yields. In the presence of tetrabuthylammonium bromide the corresponding bromide is obtained. Selective halogenation of primary hydroxyl groups in the presence of an unprotected secondary one is described. The mild reaction conditions involved are compatible with the major alcohol protecting groups as well as with acid sensitive functions like epoxides. (C) 2000 Elsevier Science Ltd.
- Gomez,Gellibert,Wagner,Mioskowski
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p. 6049 - 6052
(2007/10/03)
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- Thiocyanation of alkyl halides with alkyl thiocyanates in the presence of quaternary phosphonium halides
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Alkyl thiocyanates undergo simple SN2 reactions with the counter ions of quaternary phosphonium salts in nonpolar solvents and thiocyanate ions are liberated as the leaving ion. Depending on the nucleophile, the reaction proceeded irreversibly or reversibly. The reaction of benzyl thiocyanate with azide ions afforded a quantitative yield of benzyl azide. The reactions of alkyl thiocyanates with halide ions gave an equilibrium mixture where the reverse reaction of the alkyl halides produced with the liberated thiocyanate ions took place simultaneously. Thus, thiocyanate-halide exchange reactions between an alkyl thiocyanate and an alkyl halide were possible in the presence of a catalytic amount of a quaternary salt.
- Ohtani, Noritaka,Murakawa, Shigeki,Watanabe, Kohji,Tsuchimoto, Daisuke,Sato, Daiki
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p. 1851 - 1856
(2007/10/03)
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- Study of activation energy and order of reaction of some liquid crystals
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Liquid crystals of the type p-phenylene-di-p-n-alkoxy benzoate have been prepared. Kissinger isothermal decomposition method has been used for determination of activation energy values of liquid crystals. Kissinger's assessment for shape index of DTA peaks is used to find the order of reaction. There is no direct relationship between the carbon atoms in terminal methylene groups and Ea values. Order of reaction value decreases with increase in heating rate upto carbon atoms 10 in the terminal methylene group but beyond this the order increases or decreases.
- Mundhe
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p. 246 - 249
(2007/10/03)
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- Process for producing 1-substituted-hydantoins
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The subject is to provides a process for producing 1-substituted-hydantoins of Formula I: STR1 wherein R1 represents d hydrocarbon group which may be substituted and others, cheracterized by reacting N-sustituted-N-alkcycarbonylamnilo-acetonitrile of Formula II: STR2 wherein R2 represents an alkyl group and others, with an alkali metal hydroxides or the like and then treating with an acid.
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- Esterification of carboxylic acid salts
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Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
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- Process for producing 1-substituted-hydantoins
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The subject is to provides a process for producing 1-substituted-hydantoins of Formula I: wherein R1represents a hydrocarbon group which may be substituted and others,characterized by reacting N-substituted-N-alkoxycarbonylamino-acetonitrile of Formula II: wherein R2represents an alkyl group and others,with an alkali metal hydroxides or the like and then treating with an acid.
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- Primary and secondary 5-(alkyloxy)thianthrenium perchlorates. Characterization with 1H NMR spectroscopy, reactions with iodide and bromide ion, and thermal decomposition in solution
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A series of 5-(alkyloxy)thianthrenium perchlorates has been made in which the alkyl group is primary (1a-1p) and secondary (2a-2g). Preparations were carded out by reaction of the corresponding alkanol with thianthrene cation radical perchlorate in CH2Cl2 solution followed by precipitation of the perchlorate salt with dry ether. 1H NMR spectroscopy reveals that the presence of a stereogenic center in the alkyl group causes inequivalence in the ordinarily paired protons (e.g., H-4, H-6) of the thianthrenium ring. Reaction of iodide and bromide ion with primary alkyl-group compounds (e.g., methyl, ethyl, propyl, butyl) gave the alkyl halide in very good yield and by a second-order kinetic displacement. The second product was thianthrene 5- oxide (ThO). Rate constants for some of these reactions are reported. Reaction of secondary alkyl group compounds (e.g., 2-propyl, 2-pentyl, 2- hexyl, and 3-hexyl) with iodide ion gave good yields of alkyl iodide but also increasing evidence for a side reaction at the sulfonium sulfur, leading to I2, thianthrene, and secondary alkanol. Decomposition of some compounds at 100°C in solution (acetonitrile or 1,2-dichloroethane) was studied and gave alkene(s) and ThO.
- Zhao, Wenyi,Shine, Henry J.
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p. 695 - 702
(2007/10/03)
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- Process for the preparation of haloanthranilic acids
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The present invention relates to a process for the preparation of compounds of the general formula I STR1 in which X and Y, independently of each other, represent hydrogen, fluorine, chlorine or bromine, but cannot simultaneously represent hydrogen, characterised in that compounds of the general formula II STR2 in which X and Y are defined as above, are reacted with aqueous ammonia under copper catalysis, and to intermediates for the preparation of compounds of the general formula I.
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- Kinetics and thermochemistry of the R + HBr ? RH + Br (R = n-C3H7, isoC3H7, n-C4H9, isoC4H9, sec-C4H9 or tert-C4H9) equilibrium
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The kinetics of the reactions of n-C3H7, isoC3H7, n-C4H9, isoC4H9, sec-C4H9 and tert-C4H9 radicals, R, with HBr have been investigated in a beatable tubular reactor coupled to a photoionization mass spectrometer. The reactions were studied by a time-resolved technique under pseudo-first-order conditions, where the rate constants of R + HBr reactions were obtained by monitoring the decay of the radical as a function of time. The radical was photogenerated in situ in the flow reactor by pulsed 248 nm exciplex laser radiation. All six reactions were studied separately over a wide range of temperatures and, in these temperature ranges, the rate constants determined were fitted to an Arrhenius expression (error limits stated are 1σ + Students t values, units cm3 molecule-1 s-1): k(n-C3H7) = (1.6 ± 0.2) × 10-12 exp[+(5.4 ± 0.2) kJ mol-1/RT], k(isoC3H7) = (1.4 ± 0.2) × 10-12 exp[+(6.9 ± 0.2) kJ mol-1/RT], k(n-C4H9) = (1.3 ± 0.2) × 10-12 exp[+(6.4 ± 0.4) kJ mol-1/RT], k(isoC4H9) = (1.4 ± 0.2) × 10-12 exp[+(6.1 ± 0.2) kJ mol-1/RT], k(sec-C4H9) = (1.4 ± 0.3) × 10-12 exp[+(7.5 ± 0.3) kJ mol-1/RT] and k(tert-C4H9) = (1.2 ± 0.3) × 10-12 exp[+(8.3 ± 0.3) kJ mol-1/RT]. The kinetic information was combined with the kinetics of the Br + RH reactions to calculate the entropy and the heat of formation values for the radicals studied. The thermodynamic values were obtained at 298 K using a second-law procedure. The entropy values and enthalpies of formation are (entropy in J K-1 mol-1 and enthalpy in kJ mol-1): 284 ± 5, 100.8 ± 2.1 (n-C3H7); 281 ± 5, 86.6 ± 2.0 (isoC3H7); 329 ± 5, 80.9 ± 2.2 (n-C4H9); 316 ± 5, 72.7 ± 2.2 (isoC4H9); 330 ± 5, 66.7 ± 2.1 (sec-C4H9) and 315 ± 4, 51.8 ± 1.3 (tert-C4H9). The C-H bond strength of analogous saturated hydrocarbons derived from the enthalpy of reaction values are (in kJ mol-1): 423.3 ± 2.1 (primary C-H bond in propane), 409.1 ± 2.0 (secondary C-H bond in propane), 425.4 ± 2.1 (primary C-H bond in n-butane), 425.2 ± 2.1 (primary C-H bond in isobutane), 411.2 ± 2.0 (secondary C-H bond in n-butane) and 404.3 ± 1.3 (tertiary C-H bond in isobutane). The enthalpy of formation values are used in group additivity calculations to estimate Δf H298○ values of six pentyl and four hexyl free radical isomers.
- Seetula, Jorma A.,Slagle, Irene R.
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p. 1709 - 1719
(2007/10/03)
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- Kinetics of the nucleophilic substitution of benzyltributylammonium bromide with allyl, butyl, and benzyl chlorides and with benzyl acetate and benzyl ether
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In this study, we investigated the kinetics of the nucleophilic substitutions, RX + (BzBu3NBr) ? RBr + (BzBu3NX), where R = allyl, Bu and Bz, when X = Cl; and X = AcO and BzO when R = Bz. The forward and backward rate constants in addition to the activation energies for R = allyl and Bu were also determined. However, only the rate constants at 35°C were determined for the benzyl compounds with toluene as the solvent to reduce the reaction rate. Moreover, the effects of the structures of the groups R and the leaving groups X on the reactivity were compared. Results in this study can provide valuable information for future studies involving the phase transfer catalyzed displacements.
- Wang, Ten-Tsai,Chang, Chyi-Huang,Huang, Ting-Chia
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p. 615 - 626
(2007/10/03)
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- 2,5-reactive substituent group-containing siloles, silole polycondensates and preparation thereof
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2,5-Reactive substituent group-containing siloles of the following general formula are provided STR1 wherein R1 to R4 may be the same or different and independently represent a monovalent hydrocarbon group having from 1 to 12 carbon atoms or a hydrogen atom, and R5 and R6 may be the same or different and independently represent a group selected from monovalent hydrocarbon-substituted sulfur, selenium, silicon, germanium, tin and phosphorus, or a halogen atom. Polycondensates of the siloles and processes for preparing the siloles and polycondensates are described.
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- Quantitative treatment of micellar effects upon nucleophilic substitution
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Cationic micelles of cetyltrimethylammonium surfactants increase first-order rate constants for the basic hydrolysis of tert-butyl perbenzoate and 2-naphthyl benzoate.Dealkylation of both butyl 4-nitrobenzenesulfonate and butyl 4-bromobenzenesulfonate by halide ions in micelles of CTACl, CTABr and CTAOMs, and by azide ion in micelles of cetyltrimethylammonium mesylate (CTAOMs) have been examined.The nucleophilic aromatic substitutions of 2-chloro-3,5-dinitropyridine by OH- and N3- ions in the presence of CTABr, CTACl and CTAOMs micelles have also been examined.The rate enhancements have been treated in terms of concentration of both substrates and nucleophilic anions at the micellar surface.The anionic concentrations depend upon specific and non-specific coulombic interactions, which were calculated by solving the Poisson-Boltzmann equation (PBE).The same parameters were used in fitting data for reactions of N3-, Br- or Cl- as nucleophiles and for systems with Cl-, Br- and OMs- as inert counter-anions in CTACl, CTABr and CTAOMs, respectively.
- Al-Lohedan, Hamad A.
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p. 1707 - 1714
(2007/10/02)
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- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
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In the presence of catalytic amount of BiCl3, chloromethylsylanes can be used as chlorinating agents for alcohols, and as chloro-dealkylating agents for silyl ethers and carboxylic and sulfonic esters.The chlorination of (R)-(-)-octan-2-ol and the (R)-(-)-2-mesyloctane by TMSCl gave predominantly the (S)-(+)-2-chlorooctane with inversion of configuration at secondary carbon.According to the class of alcohol, the mechanism involves SN2, SN2' or SN1 processes.This new activation of the Si-Cl bond, probably trough a Si-Cl...BiCl3 interaction gives a hard-soft reagent that can generate a silicenium cation, was also observed with Me3SiBr, BiBr3 and Me3SiI, BiI3 systems.The reaction is also presented as a possible alcoholysis of chlorosilanes, which can lead to siloxanes in non-aqueous conditions. catalysis / halogenation / alcohol / ester / silyl ether / chlorosilane / chlorotrimethylsilane / bromotrimethylsilane / iodotrimethylsilane / siloxane / bismuth (III) halide
- Labrouillere, Mireille,Roux, Christophe Le,Oussaid, Abdelouahad,Gaspard-Iloughmane, Hafida,Dubac, Jacques
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p. 522 - 530
(2007/10/02)
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- Process for preparing phosphinyloxy propanaminium inner salt derivatives
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A process for preparing compounds of the formula STR1 where X1 and X2 are independently O or S, and R1 is as defined herein, R2, R3, and R4 are each independently straight or branched chain (C1-4)alkyl, and pharmaceutically acceptable salts, physiological hydrolyzable esters, and pro-drug forms thereof, which are useful as hypoglycemic agents.
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- 4-ARYL- AND 4-ARYLTHIO-5-HYDROXY-2(5H)-FURANONES AS INHIBITORS OF PHOSPHOLIPASE A2
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The invention provides novel 5-hydroxy-4-aryl- and 5-hy-droxy-4-(arylthio)-2(5H)-furanones of the following structure: wherein R contains from about five to about twenty carbon atoms and is defined herein; X is oxygen, sulfur, S02, NH, N(lower alkyl), N(lower acyl), aminocarbonyl, carbonyl, carbonylamino, CH2 or a carbon-carbon bond; Y is hydrogen, halogen, lower alkyl, nitro, alkylthio, perfluoroalkyl, hydroxy, or lower alkoxy(C1-C8); Z is sulfur or a carbon-carbon bond; and Q is H, an alkyl of from 1-20 carbon atoms, COR', COOR', CONHR', PO(OR')2, PO(OR')R" wherein R' and R" are independently selected from the group consisting of H, an alkyl of from 1-20 carbon atoms, phenyl, and substituted phenyl and prodrugs thereof and pharmaceutically acceptable salts thereof. Pharmaceutical compositions comprising these compounds, methods of using these compounds as inhibitors of inflammation and for treating other diseases characterized by the overproduction of arachidonic acid metabolites, intermediates and methods of preparing these compounds are also provided.
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- Synthetic Microbial Chemistry, XXVI. - Absolute Configuration of (+)-Xanthocidin as Determined by the Synthesis of Its Enantiomers of Known Stereochemistry
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The absolute configuration of the antibiotic (+)-xanthocidin (4,5-dihydroxy-5-isopropyl-4-methyl-2-methylene-3-oxocyclopentane-1-carboxylic acid, 1) was shown to be 1R,4S,5S by the synthesis of its enantiomers.Lipase AK (Amano) was used for the key resolution step, and the absolute configuration of the resolved intermediate (+)-16 was determined by X-ray analysis of its (1S)-camphanic ester (+)-20. - Key Words: Antibiotics / Asymmetric acylation / Lipases / Streptomyces xanthocidicus / Xanthocidin
- Mori, Kenji,Horinaka, Akio,Kido, Masaru
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p. 817 - 826
(2007/10/02)
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- REACTION OF ALCOHOLS WITH BROMINE
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Framework hydrocarbons react with bromine in water to form tertiary alcohols.In the absence of moisture the various alcohols react with bromine by a nucleophilic substitution mechanism, forming alkyl bromides.
- Baklan, V. F.,Khil'chevskii, A. N.,D'yakovskaya, V. M.,Sologub, L. S.,Kukhar, V. P.
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p. 454 - 456
(2007/10/02)
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- Process for preparing fibrinogen receptor antagonists
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The invention is a highly efficient synthesis for making compounds of the formula: STR1 wherein: R1 is a six member saturated or unsaturated heterocyclic ring containing one or two heterocyclic atoms wherein the heteroatoms are N; or NR6, wherein R6 is H or C1-10 alkyl; m is an integer from two to six; and R4 is aryl, C1-10 alkyl, or C4-10 aralkyl.
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- Method of dehydrating organic oxygenates
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Aqueous solutions of organic oxygenates, such as ethylene glycol may be dehydrated by
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