3552-01-0Relevant articles and documents
Intramolecular carbometalation of functionalized terminal alkynes via low-valent titanium complexes
Morlender-Vais,Solodovnikova,Marek
, p. 1849 - 1850 (2000)
Treatment of δ- and γ-functionalized monosubstituted alkynes with diisopropoxy(η2-propene)titanium induces an intramolecular cyclisation to afford the 4- and 5-membered cycloalkanols in good overall yields.
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
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
, (2021/08/30)
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
Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
supporting information, p. 9925 - 9937 (2021/06/30)
A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
Cytochrome P450 catalyzed oxidative hydroxylation of achiral organic compounds with simultaneous creation of two chirality centers in a single C-H activation step
Roiban, Gheorghe-Doru,Agudo, Ruben,Reetz, Manfred T.
, p. 8659 - 8663 (2014/08/18)
Regio- and stereoselective oxidative hydroxylation of achiral or chiral organic compounds mediated by synthetic reagents, catalysts, or enzymes generally leads to the formation of one new chiral center that appears in the respective enantiomeric or diastereomeric alcohols. By contrast, when subjecting appropriate achiral compounds to this type of C-H activation, the simultaneous creation of two chiral centers with a defined relative and absolute configuration may result, provided that control of the regio-, diastereo-, and enantioselectivity is ensured. The present study demonstrates that such control is possible by using wild type or mutant forms of the monooxygenase cytochrome P450 BM3 as catalysts in the oxidative hydroxylation of methylcyclohexane and seven other monosubstituted cyclohexane derivatives.
Microwave-assisted domino hydroformylation/cyclization reactions: Scope and limitations
Airiau, Etienne,Chemin, Claire,Girard, Nicolas,Lonzi, Giacomo,Mann, Andre,Petricci, Elena,Salvadori, Jessica,Taddei, Maurizio
experimental part, p. 2901 - 2914 (2010/10/21)
Hydroformylation of alkenes can be carried out in short time and with low syngas pressure under microwave (MW) dielectric heating. Alkenes, carrying O-, N-, or C-nucleophilic fragments, can be designed for domino reactions, mainly cyclocondensations. Ally
Solutions of anhydrous lanthanide salts and its preparation
-
, (2008/06/13)
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.
Highly efficient alkylation to ketones and aldimines with Grignard reagents catalyzed by zinc(II) chloride
Hatano, Manabu,Suzuki, Shinji,Ishihara, Kazuaki
, p. 9998 - 9999 (2007/10/03)
A highly efficient alkylation to ketones and aldimines with Grignard reagents in the presence of catalytic trialkylzinc(II) ate complexes derived from ZnCl2 (10 mol %) in situ was developed. This simple Zn(II)-catalyzed alkylation could minimize the well-known but serious problems with the use of only Grignard reagents, which leads to reduction and aldol side products, and the yield of desired alkylation products could be improved. Copyright
Soluble lanthanide salts (LnCl3,·2 LiCl) for the improved addition of organomagnesium reagents to carbonyl compounds
Krasovskiy, Arkady,Kopp, Felix,Knochel, Paul
, p. 497 - 500 (2007/10/03)
(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.
Photolysis of 1-alkylcycloalkanols in the presence of (diacetoxyiodo) benzene and I2. Intramolecular selectivity in the β-scission reactions of the intermediate 1-alkylcycloalkoxyl radicals
Antunes, Carla S. Aureliano,Bietti, Massimo,Lanzalunga, Osvaldo,Salamone, Michela
, p. 5281 - 5289 (2007/10/03)
The C-C β-scission reactions of 1-alkylcycloalkoxyl radicals, generated photochemically by visible light irradiation of CH2Cl 2 solutions containing the parent 1-alkylcycloalkanols, (diacetoxy)-iodobenzene (DIB), and I2, have been investigated through the analysis of the reaction products. The 1-alkylcycloalkoxyl radicals undergo competition between ring opening and C-alkyl bond cleavage as a function of ring size and of the nature of the alkyl substituent. With the 1-propylcycloheptoxyl, 1-propylcyclooctoxyl, and 1-phenylcyclooctoxyl radicals, formation of products deriving from an intramolecular 1,5-hydrogen atom abstraction reaction from the cycloalkane ring has also been observed. The results are discussed in terms of release of ring strain associated to ring opening, stability of the alkyl radical formed by C-alkyl cleavage, and with cycloheptoxyl and cyclooctoxyl radicals, also in terms of the possibility of achieving a favorable geometry for intramolecular hydrogen atom abstraction.
Microreaction technology as a novel approach to drug design, process development and reliability
Taghavi-Moghadam, Shahriyar,Kleemann, Axel,Golbig, Klaus Georg
, p. 652 - 658 (2013/09/07)
This paper focuses on the application of microreaction technology in the life science industry. Certain features of microreaction technology, for example, mixing, heat transfer, and residence time distribution, are discussed. Important advantages such as high operational safety and the possibility to transfer the experimental results directly from laboratory to the production of pilot-plant scales are mentioned. Potential application fields in the drug discovery and development processes, from research to production, by including chemical synthesis of different targets in the case of the quinoline acid derivative (ciprofloxacin) and the Paal - Knorr pyrrole synthesis are presented.
