- Chemistry of fluorinated vinamidinium salts: Novel reactions of β-trifluoromethyl vinamidinium salt with Grignard reagents
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β-Trifluoromethyl vinamidinium salt 1 reacted cleanly with a variety of Grignard reagents 2 in tetrahydrofuran under reflux for 3 h to produce a mixture of diastereoisomers (dl and meso) of the corresponding difluoromethylene compounds 3 in good to excellent yields.
- Yamanaka, Hiroki,Uegaki, Tomonori,Ishihara, Takashi,Kubota, Toshio,Gupton, John T.
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- A NOVEL, CONTINUOUS HIGH-YIELD SYNTHESIS OF GRIGNARD REAGENTS
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A continuous process for the production of Grignard reagents, in particular, allylmagnesium chloride is described.The yield and purity of the Grignard reagent are both significantly higher then those normally obtained by use of conventional batch procedures.Disproportionation of the Grignard reagent to insoluble magnesium chloride presented the major technical problem in the process, though, of course, the yield of active "allyl" is uneffected.
- Jennings, J. R.
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- Scalable Continuous Synthesis of Grignard Reagents from in Situ-Activated Magnesium Metal
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The continuous synthesis of Grignard reagents has been investigated under continuous processing conditions using Mg turnings at variable liquid throughputs and concentrations. A novel process window easily accessible through continuous processing was employed, namely, using a large molar access of Mg turnings within the reactor and achieving Mg activation by mechanical means. A laboratory and a 10-fold-increased pilot-scale reactor setup were built and evaluated, including integrated inline analytics via ATR-IR measurements. The main goal of this work was to explore the full potential of classic Grignard reagent formation through the use of scalable flow chemistry and to allow for fast and safe process optimization. It was found that on both the laboratory and pilot scales, full conversion of the employed halides could be achieved with a single passage through the reactor. Furthermore, Grignard reagent yields of 89-100% were reached on the laboratory scale.
- Deitmann, Eva,G?ssl, Lars,Hofmann, Christian,L?b, Patrick,Menges-Flanagan, Gabriele
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p. 315 - 321
(2020/03/10)
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- Redox-Active Ligand-Assisted Two-Electron Oxidative Addition to Gallium(II)
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The reaction of digallane (dpp-bian)Ga?Ga(dpp-bian) (2) (dpp-bian=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with allyl chloride (AllCl) proceeded by a two-electron oxidative addition to afford paramagnetic complexes (dpp-bian)Ga(η1-All)Cl (3) and (dpp-bian)(Cl)Ga?Ga(Cl)(dpp-bian) (4). Treatment of complex 4 with pyridine induced an intramolecular redox process, which resulted in the diamagnetic complex (dpp-bian)Ga(Py)Cl (5). In reaction with allyl bromide, complex 2 gave metal- and ligand-centered addition products (dpp-bian)Ga(η1-All)Br (6) and (dpp-bian-All)(Br)Ga?Ga(Br)(dpp-bian-All) (7). The reaction of digallane 2 with Ph3SnNCO afforded (dpp-bian)Ga(SnPh3)2 (8) and (dpp-bian)(NCO)Ga?Ga(NCO)(dpp-bian) (9). Treatment of GaCl3 with (dpp-bian)Na in diethyl ether resulted in the formation of (dpp-bian)GaCl2 (10). Diorganylgallium derivatives (dpp-bian)GaR2 (R=Ph, 11; tBu, 14; Me, 15; Bn, 16) and (dpp-bian)Ga(η1-All)R (R=nBu, 12; Cp, 13) were synthesized from complexes 3, 10, Bn2GaCl, or tBu2GaCl by salt metathesis. The salt elimination reaction between (dpp-bian)GaI2 (17) and tBuLi was accompanied by reduction of both the metal and the dpp-bian ligand, which resulted in digallane 2 as the final product. Similarly, the reaction of complex 10 with MentMgCl (Ment=menthyl) proceeded with reduction of the dpp-bian ligand to give the diamagnetic complex [(dpp-bian)GaCl2][Mg2Cl3(THF)6] (18). Compounds 11, 12, 13, 15, and 16 were thermally robust, whereas compound 14 decomposed when heated at reflux in toluene to give complex (dpp-bian-tBu)GatBu2 (19). Both complexes 7 and 19 contain R-substituted dpp-bian ligand: in the former compound the allyl group was attached to the imino-carbon atom, whereas in complex 19, the tBu group was situated on the naphthalene ring. Crystal structures of complexes 3, 8, 9, 10, 13, 14, 18, and 19 were determined by single-crystal X-ray analysis. The presence of dpp-bian radical anions in 3, 6, 8, and 10–16 was determined by ESR spectroscopy.
- Fedushkin, Igor L.,Dodonov, Vladimir A.,Skatova, Alexandra A.,Sokolov, Vladimir G.,Piskunov, Alexander V.,Fukin, Georgii K.
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p. 1877 - 1889
(2018/01/27)
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- PROCESS FOR PRODUCING PHOSPHONIUM BORATE COMPOUND, NOVEL PHOSPHONIUM BORATE COMPOUND, AND METHOD OF USING THE SAME
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The invention relates to a phosphonium borate compound represented by Formula (I) (hereinafter, the compound (I)). The invention has objects of providing (A) a novel process whereby the compound is produced safely on an industrial scale, by simple reaction operations and in a high yield; (B) a novel compound that is easily handled; and (C) novel use as catalyst. ????????Formula (I) : (R1)(R2)(R3)PH·BAr4?????(I) wherein R1, R2, R3 and Ar are as defined in the specification. The process (A) includes reacting a phosphine with a) HCl or b) H2SO4 to produce a) a hydrochloride or b) a sulfate; and reacting the salt with a tetraarylborate compound. The compound (B) has for example a secondary or tertiary alkyl group as R1 and is easily handled in air without special attention. The use (C) is characterized in that the compound (I) is used instead of an unstable phosphine compound of a transition metal complex catalyst for catalyzing C-C bond, C-N bond and C-O bond forming reactions and the compound produces an effect that is equal to that achieved by the transition metal complex catalyst.
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Page/Page column 76-77
(2008/06/13)
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- Process for preparing 1-bromoalkylbenzene derivatives and intermediates thereof
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A 1-bromoalkylbenzene derivative is prepared by reacting a phenylalkene derivative with hydrogen bromide in the presence of a non-polar solvent. The phenylalkene derivative is prepared by reacting an alkenyl halide with metal magnesium to form a Grignard reagent, and then reacting the Grignard reagent with a benzyl halide derivative. An allyl Grignard reagent is prepared by reacting continuously an allyl halide derivative with metal magnesium in an organic solvent, in which the allyl halide derivative and metal magnesium are continuously added to the reaction system and the allyl Grignard reagent formed is continuously removed from the reaction system. The processes provide the intended compounds in high yields, high selectivities and high purities.
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- Diphenylsiloxane oligomers functionalized at both terminal and method for the preparation thereof
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There is disclosed a diphenylsiloxane oligomer functionalized at both terminals, and methods for the preparation thereof, said oligomer having the following general formula G-(OSi(Ph)2)m O--G wherein Ph denotes a phenyl radical, m is 3 to 50 and G is has a formula independently selected from the group consisting of STR1 in which R1 is independently selected from the group consisting of hydrogen and a monovalent hydrocarbon group having 2 to 8 carbon atoms, said monovalent hydrocarbon group excluding phenyl, tolyl, xylyl, and ethylphenyl radicals, R is independently selected from the group consisting of R1, methyl radical and phenyl radical, Q is a divalent hydrocarbon group and n is an integer having a value of 1 to 3.
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- Infrared and nuclear magnetic resonance spectroscopic studies of the structure and dynamics of allylic magnesium compounds
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The infrared spectra of allyl- and methallyl-d2-magnesium bromides have two double bond stretching bands, corresponding to C=CH2 and C=CD2 groups in equilibrating allylic isomers. The methylene resonances in the 13C NMR spectra of allylmagnesium bromide and chloride and methallylmagnesium bromide are broadened at low temperatures by an exchange process which appears to be the interconversion between the classical unsymmetrical allylic structures. Analogous changes are seen in the spectrum of 1,3-dimethylallylmagnesium chloride and in the proton NMR spectrum of allylmagnesium bromide. Rate constants and activation parameters for the exchange have been determined from the line broadenings. Unlike the Grignard reagent, the methylene resonances of diallylmagnesium in tetrahydrofuran are not significantly broadened at reduced temperature, and the deuterated reagent does not have two distinct double bond stretching bands in the IR spectrum.
- Hill, E. Alexander,Boyd, Winston A.,Desai, Hemnalini,Darki, Amir,Bivens, Lymel
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- Mechanical Activation of Magnesium Turnings for the Preparation of Reactive Grignard Reagents
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Preactivation of magnesium by dry stirring in an inert atmosphere is highly beneficial for the clean synthesis of reactive allylic or benzylic organomagnesium chlorides.This procedure routinely produces 0.4 M solutions of the Grignard reagent in diethyl ether free from coupling products.The purity may be directly assayed by 13C spectroscopy.Using spin saturation transfer techniques, the rate constant for interconversion of the enantiomers of (1-phenyl-2-methylpropyl)magnesium chloride in Et2O at 25 deg C was shown to be -1.Electron microscopy has been used to define the surface changes occurring during the dry stirring of magnesium turnings.
- Baker, Karen V.,Brown, John M.,Hughes, Nigel,Skarnulis, A. Jerome,Sexton, Ann
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p. 698 - 703
(2007/10/02)
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- Use of Magnesium Anthracene * 3 THF in Synthesis: Generation of Grignard Compounds and Other Reactions with Organic Halides
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The course (a), (b), (c) (Scheme 1) of the reaction of magnesium anthracene * 3 THF (1) with organic halides (RX) is dependent on the nature of RX.With alkyl halides in THF 1 reacts as a nucleophile, whereby primary as well as secondary alkyl halides produce dialkyldihydroanthracenes (4-4'') and tertiary alkyl halides yield primarily monoalkyl-substituted dihydroanthracenes (2, 2').With bromo- and iodobenzene in THF 1 reacts predominantly as a radical with H atom abstraction from the solvent affording benzene and 9.The formation of Grignard compounds (5) and anthracene (6), originating from primary and secondary alkyl and aryl halides and 1 in toluene or ether at elevated temperatures, is not caused by the reaction of 1 but by the "active magnesium" (Mg*) formed by decomposition of 1 in these solvents.In contrast, allyl, propargyl, and benzyl halides react with 1 independently of the solvent under mild conditions to produce 5 and 6.Allyl- and the difficultly accessible allenylmagnesium chloride can be prepared in THF at -78 and 0 deg C, respectively, from the corresponding halides and ordinary Mg powder via catalytic amounts of 1.
- Bogdanovic, Borislav,Janke, Nikolaus,Kinzelmann, Hans-Georg
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p. 1507 - 1515
(2007/10/02)
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- Magnesium Adducts of Substituted Anthracenes - Preparation and Properties
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2-Methyl-, 1,4-dimethyl-, 9-methyl-, 9-ethyl-, 9,10-dimethyl-, and 9-phenylanthracene (1a-f) react with magnesium in THF at room temperature to afford the corresponding substituted magnesium anthracenes 2a-f. 9,10-Diphenylanthracene (1g), however, reacts with magnesium under the same conditions to produce the deep-blue magnesium bis(9,10-diphenylanthracenide) * 6 THF (4g).Upon heating to 60 deg C in THF, 4g reversibly dissociates to give magnesium 9,10-diphenylanthracene * 3 THF (2g) and 1g, while prolonged heating at 60 deg C causes decomposition of 2g to active magnesium (Mg*) and 1g.In THF 2a-c, e, and f exhibit temperature-dependent equilibria with 1a-c, e, and f and magnesium.Compared with magnesium anthracene * 3 THF (2), these equilibria are strongly shifted toward substituted anthracenes and magnesium, and only at 0 deg C high conversions are achieved.The magnesium exchange between 2 and the substituted anthracenes 1a, b, and f in THF has been experimentally verified. 2a, e, and f react with organic halides in the same way as 2, however, in the case of allyl, propargyl, and benzyl chloride the yields of Grignard compounds are lower than for 2; with bromobenzene, the tendency for the radical transfer reaction is stronger than for 2.Magnesium 9,10-dimethylanthracene (2e) reacts with ethyl acetate to give the bicyclic tertiary alcohol 9 by an intramolecular C-C coupling reaction.
- Bogdanovic, Borislav,Janke, Nikolaus,Kinzelmann, Hans-Georg,Seevogel, Klaus,Treber, Joachim
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p. 1529 - 1535
(2007/10/02)
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- Process for using finely divided highly reactive magnesium
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The present invention relates to a process for preparing a finely divided, highly reactive magnesium from magnesium hydride, magnesium anthracene and/or its derivatives or magnesium butadiene and/or its alkyl or phenyl derivatives, which process is characterized in that the respective magnesium-containing compound is thermally decomposed at a pressure from 10-6 to 1 bar, the decomposition being carried out in the presence of a co-reactant of a consecutive reaction, or such co-reactant being added only after completion of the precipitation of the magnesium, or in the absence of such co-reactant, the magnesium obtained by said decomposition being isolated as a powder, and to the use of the finely divided, highly reactive magnesium for inserting magnesium into poorly reactive C--X bonds, wherein X denotes heteroatoms such as halogen, oxygen, sulfur, nitrogen, phosphorus, and the resulting organomagnesium compound may be used in a consecutive reaction according to a per se known method, and for the reversible preparation of active magnesium hydride by reaction with molecular hydrogen at a pressure of from 1 to 2 bar and at a temperature of from 150° C. to 250° C.
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- AROMATIC ANNULATION WITH BISPHENYLTHIONIUM IONS
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The chemospecific production and intramolecular aromatic electrophilic substitution (annulation) of bis(phenylthio)carbocations (bisphenylthionium ions) has been studied using appropriate model compounds.The annulation reaction is very sensitive to the Lewis acid initiator and also the solvent.The best reaction conditions were found to be a suspension of silver trifluoromethanesulfonate in dichloromethane.Annulation of six-membered rings onto alkylbenzene and five- and seven-membered rings onto activated benzenes have been achieved.
- Manas, Abdul Rahman Bin,Smith, Robin A. J.
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p. 1847 - 1856
(2007/10/02)
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