- Development of a Scalable Lanthanide Halide/Quaternary Ammonium Salt System for the Nucleophilic Addition of Grignard Reagents to Carbonyl Groups and Application to the Synthesis of a Remdesivir Intermediate
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This manuscript describes the development and implementation of a scalable additive system, consisting of a lanthanide salt and a solubilizing quaternary ammonium salt, to improve the yield and robustness of the addition of an organomagnesium reagent to a
- Brak, Katrien,Bremner, W. Stacy,Brown, Angela M.,Chtchemelinine, Andrei,Heumann, Lars,Kerschen, James A.,Stevens, Andrew C.,Subotkowski, Witold,Vieira, Tiago,Wolfe, Lydia C.,Xu, Boran,Yu, Chia-Yun
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- A novel and efficient method for the preparation of unstable tetramethylzirconium and its application using a microflow system
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We have developed a novel and efficient method for the preparation of unstable tetramethylzirconium and its application to the synthesis of tetrakis(N-methylethylamido)zirconium and dimethylbis(indenyl)zirconium using a microflow system.
- Uehata, Koji,Nishida, Mayumi,Nishida, Atsushi
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supporting information; experimental part
p. 73 - 75
(2012/03/13)
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- Observation of 1,3-diketones formation in the reaction of bulky acyl chlorides with methyllithium
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The formation of 1,3-diketones was observed in the reactions of bulky acyl chlorides with methyllithium. The reaction products depend on the steric hindrance around the carbonyl group of the acyl chloride and the electronic effect of the group(s) linked to the carbonyl. When the steric hindrance around the carbonyl group of the acyl chloride is big enough, the 1,3-diketone is the only product. In the case of the moderate hindrance around the carbonyl group of the acyl chloride, a moderate yield of 1,3-diketone is obtained and some tertiary alcohol is generated. When there is no steric hindrance around the carbonyl group of the acyl chloride, the tertiary alcohol is the only product. When the steric hindrance around the carbonyl group is moderate and an electron-donating group is connected to the carbonyl of the acyl chloride, all three products-ketone, 1,3-diketone and tertiary alcohol-can be isolated from the reaction mixture after long reaction times.
- Zhang, Jian,Yang, Nianfa,Yang, Liwen
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experimental part
p. 6415 - 6423
(2012/09/08)
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- Solutions of anhydrous lanthanide salts and its preparation
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The present invention relates to anhydrous solutions of MX 3 €¢z LiA in a solvent, wherein M is a lanthanide including lanthanum, or yttrium or indium; z > 0; and X and A are independently or both monovalent anions, preferably Cl, Br or I. The solution is readily prepared by dissolving or suspending MX 3 or its hydrate and z equiv LiA in water or hydrophilic solvents, or mixtures thereof, removing the solvent under vacuum and dissolving the resulting powder in another solvent. The solution of MX 3 €¢z LiA can advantageously be used e.g. in addition reactions of Grignard reagents to ketones and imines. Even the catalytic use of MX 3 €¢z LiA is possible. Also claimed are a method for preparing the anhydrous solutions, the use of such solution in a chemical reaction and chemical compositions MX 3 €¢z LiA, with M, z, X and A as indicated above.
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- Soluble lanthanide salts (LnCl3,·2 LiCl) for the improved addition of organomagnesium reagents to carbonyl compounds
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(Chemical Equation Presented) Easy-to-prepare solutions of LnCl 3·2 LiCl (Ln = La, Ce, Nd) (0.3-0.5 M in THF) are a unique source of soluble lanthanide salts with versatile applications in organic synthesis. These salts can serve as promoters or catalysts for the addition of organometallic compounds to sterically hindered, enolizable or α,β-unsaturated ketones or imines.
- Krasovskiy, Arkady,Kopp, Felix,Knochel, Paul
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p. 497 - 500
(2007/10/03)
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- SOLVENTS CONTAINING CYCLOALKYL ALKYL ETHERS AND PROCESS FOR PRODUCTION OF THE ETHERS
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The present inventions are (A) a solvent comprising at least one cycloalkyl alkyl ether (1) represented by the general formula: R1-O-R2 (wherein R1 is cyclopentyl or the like; and R2 is C1-10 alkyl or the like); (B) a method of preparations the ethers (1) characterized by reacting an alicyclic olefin with an alcohol in the presence of an acid ion-exchange resin having a water content of 5 wt% or less. The solvent is useful as cleaning solvent for electronic components, precision machinery components or the like, reaction solvent using various chemical reactions, extraction solvent for extracting objective organic substances, solvent or remover for electronic and electrical materials, and so on. The process enables industrially advantageous production of the objective cycloalkyl alkyl ethers (1).
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- How does organic structure determine organic reactivity? The effect of ortho-dimethyl groups on the nucleophilic substitution and alkene-forming elimination reactions of ring-substituted cumyl derivatives
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The addition of a pair of ortho-methyl groups to ring-substituted cumyl derivatives to give the corresponding 2,6-dimethylcumyl derivatives X-1-Y leads to modest (5-fold) changes in the observed rate constant for reaction in 50:50 (v:v) trifluoroethanol-
- Amyes, Tina L.,Mizerski, Tadeusz,Richard, John P.
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p. 922 - 933
(2007/10/03)
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- Ortho Methyl Group Effects in Cumyl Systems
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In an attempt to evaluate the steric effect of ortho methyl groups on the stability of the cumyl radical, 2,2',4,4',6,6'-hexamethylazocumene (6) was synthesized and its rate of decomposition was measured.The fact that 6 decomposes 40 times faster than azocumene is attributed to a ground state steric effect.Calculations on the mesitylcumyl radical 1 and cation 2 show both systems to be substantially nonplanar with dihedral angles of 48 deg and 35 deg, respectively.Calculated charge distributions for cation 2 corroborate previously obtained NMR results which showed substantial loss of charge delocalization.
- Timberlake, Jack W.,Pan, Dawei,Murray, Jane,Jursic, Branko S.,Chen, Tonghua
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p. 5295 - 5298
(2007/10/02)
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- Chemoselective Addition of Organotitanium Reagents to Carbonyl Compounds
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The conversion of classical carbanions such as RMgX, RLi, or deprotonated nitriles, sulfones, and carboxylic esters into titanium analogs results in reagents which add chemoselectively to carbonyl compounds in the presence of other functional groups.The standard titanating agent is chlorotriisopropoxytitanium (1).Grignard-type reactions and aldol additions are aldehyde-selective in the presence of ketones.Other functional groups such as alkyl and aryl halides, esters, amides as well as nitro and cyano moieties are tolerated.Discrimination between two aldehydes or two ketones is also possible.Replacing alkoxy ligands by methyl groups at titanium increases reactivity dramatically, relative rates increasing in the series CH3Ti(OCHMe2)3 (CH3)2Ti(OCHMe2)2 (CH3)4Ti.The latter reagent and its zirconium analog methylate sterically hindered and/or enolizable ketones which normally fail to undergo Grignard reactions.The ate complex H2C=CHCH2Ti(OCHMe2)4MgCl (63) is aldehyde-selective, while the amino analog H2C=CHCH2Ti(NMe2)4MgCl (64) adds selectively to ketones in the presence of aldehydes.
- Reetz, Manfred T.,Westermann, Juergen,Steinbach, Rainer,Wenderoth, Bernd,Peter, Roland,et al.
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p. 1421 - 1440
(2007/10/02)
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- ARYLVANADIUM-VERBINDUNGEN. XI. ZUR REAKTION VON TRIMESITYLVANADIUM MIT KETONEN
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Trimesitylvanadium in solution reacts with a series of ketones.Depending upon the structures of the ketones these reactions yield olefins, alcohols or a radical, respectively.Sterically hindered ketones only form coordination compounds with trimesitylvana
- Kreisel, G.,Seidel, W.
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p. 301 - 306
(2007/10/02)
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