20344-52-9Relevant academic research and scientific papers
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.
supporting information, 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.
Di-tert-butylmagnesium as an atom-efficient, carbon-centred base reagent for the preparation of silyl enol ethers from ketones
Kerr, William J.,Watson, Allan J. B.,Hayes, Douglas
scheme or table, p. 1386 - 1390 (2009/04/06)
Di-tert-butylmagnesium has been found to be a reactive, yet non-nucleophilic and non-reductive, carbon-centred base for the deprotonation of a series of ketones. This reagent demonstrates equally high reactivity when used as either the pre-formed reagent, or in a more accessible one-pot protocol from the parent Grignard reagent, and offers improved atom-efficiency over more traditionally employed bases. Georg Thieme Verlag Stuttgart.
Solutions of anhydrous lanthanide salts and its preparation
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, (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.
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.
Stereochemical Investigations of Samarium(II) Iodide-Promoted 5-Exo and 6-Exo Ketyl-Olefin Radical Cyclization Reactions
Molander, Gary A.,McKie, Jeffrey A.
, p. 872 - 882 (2007/10/02)
Samarium(II) iodide (SmI2)-promoted ketyl cyclizations of several substituted, unsaturated ketones, providing various cyclpentyl and cyclohexyl systems, have been investigated.The resulting experiments provide stereochemical insight into these reactions and in addition outline the synthetic potential of these 5-exo and 6-exo radical cyclization processes.
The functionalization of saturated hydrocarbons. Part 24. The use of tert-butyl hydroperoxide: GoAggIV and GoAggV
Barton, Derek H. R.,Chavasiri, Warinthorn
, p. 19 - 30 (2007/10/02)
The use of tert-butyl hydroperoxide as an oxidant in Gif-type systems (GoAggIV and GoAgfV) catalyzed by various Fe(III) species is examined. Regioselectivity studids of these systems have revealed several characteristics similar to those observed for other prdviously reported Gif-type reactions. A common rdaction pathway for the GoAggIV and GoAggV oxidation systems and other Gif-type reactions (from alkane via alkyl hydroperoxide to ketone or alcohol) is seen.
Synthesis of α-Hydroxy Ketones by Direct, Low-Temperature, in Situ Nucleophilic Acylation of Aldehydes and Ketones by Acyllithium Reagents
Seyferth, Dietmar,Weinstein, Robert M.,Hui, Richard C.,Wang, Wei-Liang,Archer, Colin M.
, p. 5620 - 5629 (2007/10/02)
The reaction of n-, sec-, and tert-butyllithium with CO at atmospheric pressure at -110 and -135 deg C in the appropriate solvent system in the presence of ketones and aldehydes generates the acyllithium, RC(O)Li, which reacts with the carbonyl compound to give the α-hydroxy ketone, generally in good yield.Reactions with aldehydes are limited in scope, working well with the t-BuLi-derived acyllithium reagents, but not with n-BuC(O)Li.
High-pressure glycosylations of unreactive alcohols and the formation of N-glycosyl collidinium salts.
Dauben,Koehler
, p. 47 - 56 (2007/10/02)
The yields of disaccharide glycosylation products in tetramethylammonium bromide or silver triflate-collidine activated reactions between hindered alcohols and glycosyl halides were not greatly ++affected when a pressure of 15 kbar was applied. The format
