51440-57-4Relevant articles and documents
Dual-gold(I)-generated trifluoromethylation of terminal alkynes with Togni's reagent
Siah, Huey-San Melanie,Fiksdahl, Anne
supporting information, p. 24 - 33 (2017/03/10)
The interaction of a Au(I) catalyst (JohnPhosAu(I)-MeCN/SbF6) and the Togni's reagent 1, as a source of electrophilic trifluoromethyl group, has been studied in order to develop gold-catalysed alkyne trifluoromethylation reactions. Alkyne-CF3products were prepared in moderate yields (up to 46%) by electrophilic trifluoromethylation of terminal arylalkynes with Togni's reagent 1 in the presence of sub-stoichiometric amounts of gold catalyst (25%). The proposed addition-elimination reaction mechanism proceeds through a Au-Togni Reagent complex with a linear Togni Reagent-O-Au(I)-P-(phosphane) coordination mode (X-ray analysis). Alkyne deprotonation gives rapid formation of protonated Togni Reagent and a σ,π-acetylide dual-Au complex, confirmed by X-ray analysis. It was shown that the σ,π-dual-Au complex activates for trifluoromethylation, most likely by transfer of a [LAu]+fragment to the alkyne substrate. The resulting reactive π-Au+-alkyne intermediate probably undergoes O-/CF3-addition of Togni Reagent, and final elimination of Togni alcohol gives the alkyne-CF3product.
Coupling Reaction of Enol Derivatives with Silyl Ketene Acetals Catalyzed by Gallium Trihalides
Nishimoto, Yoshihiro,Kita, Yuji,Ueda, Hiroki,Imaoka, Hiroto,Chiba, Kouji,Yasuda, Makoto,Baba, Akio
supporting information, p. 11837 - 11845 (2016/08/05)
A cross-coupling reaction between enol derivatives and silyl ketene acetals catalyzed by GaBr3took place to give the corresponding α-alkenyl esters. GaBr3showed the most effective catalytic ability, whereas other metal salts such as BF3?OEt2, AlCl3, PdCl2, and lanthanide triflates were not effective. Various types of enol ethers and vinyl carboxylates as enol derivatives are amenable to this coupling. The scope of the reaction with silyl ketene acetals was also broad. We successfully observed an alkylgallium intermediate by using NMR spectroscopy, suggesting a mechanism involving anti-carbogallation among GaBr3, an enol derivative, and a silyl ketene acetal, followed by syn-β-alkoxy elimination from the alkylgallium. Based on kinetic studies, the turnover-limiting step of the reaction using a vinyl ether and a vinyl carboxylate involved syn-β-alkoxy elimination and anti-carbogallation, respectively. Therefore, the leaving group had a significant effect on the progress of the reaction. Theoretical calculations analysis suggest that the moderate Lewis acidity of gallium would contribute to a flexible conformational change of the alkylgallium intermediate and to the cleavage of the carbon?oxygen bond in the β-alkoxy elimination process, which is the turnover-limiting step in the reaction between a vinyl ether and a silyl ketene acetal.
Dynamic kinetic asymmetric [3 + 2] annulation reactions of aminocyclopropanes
De Nanteuil, Florian,Serrano, Eloisa,Perrotta, Daniele,Waser, Jerome
supporting information, p. 6239 - 6242 (2014/05/20)
We report the first example of a dynamic kinetic asymmetric [3 + 2] annulation reaction of aminocyclopropanes with both enol ethers and aldehydes. Using a Cu catalyst and a commercially available bisoxazoline ligand, cyclopentyl- and tetrahydrofurylamines were obtained in 69-99% yield and up to a 98:2 enantiomeric ratio using the same reaction conditions. The method gives access to important enantio-enriched nitrogen building blocks for the synthesis of bioactive compounds.
Gallium tribromide catalyzed coupling reaction of alkenyl ethers with ketene silyl acetals
Nishimoto, Yoshihiro,Ueda, Hiroki,Yasuda, Makoto,Baba, Akio
supporting information; experimental part, p. 8073 - 8076 (2012/08/29)
A 'Ga'llant couple: The α-alkenylation of esters was accomplished by GaBr3-catalyzed coupling between alkenyl ethers and ketene silyl acetals. In this reaction system, various alkenyl ethers, including those with vinyl and substituted alkenyl groups, were applicable, and the scope of applicable ketene silyl acetals was sufficiently broad. The mechanism is also discussed. Copyright
Alkylenation with Geminal Dialuminoalkane Reagents: The Synthesis of Olefins from Ketones
Piotrowski, Andrzej M.,Malpass, Dennis B.,Boleslawski, Marek P.,Eisch, John J.
, p. 2829 - 2835 (2007/10/02)
Bis(dichloroalumino)methane (BDAM, 1) has been synthesized in high yield from aluminum powder and methylene chloride by a published procedure carefully modified for safety.By the screening away of aluminum metal fine particles and the gradual addition of methylene bromide promoter over the course of reaction, a safe procedure was attained.Although 1 itself was a poor methylenating agent for ketones, its dietherate complex was distinctly more reactive.By exchanging half the halogens of 1 with Me3Al, MeMgBr, or Et3Al, two very effective methylenating agents for ketones, namely CH2(AlClMe)2 (2) and CH2(AlClEt)2 (3), were obtained.As diether ates with Et2O or THF, 2 and 3 smoothly converted a broad variety of ketones (aliphatic, alicyclic, and aromatic) into their corresponding methylene derivatives, with little or no competitive alkylation or reduction.A titanium-modified reagent, Cl2AlCH2TiCl3 (4), was also effective toward ketones, but gave only low conversions of esters to vinyl ethers.Finally, as an example of a multicarbon, alkylenating agent, the reagents 5-7 ((R2Al)2CH(CH2)4CH3, 5, R = Et; 6, R = Cl; and 7, R = Cl or Et) were examined.Good to fair yields of alkylenation were obtained with aromatic ketones, but aliphatic ketones underwent alkylation, hydride reduction, and/or aldol condension.The great influence of alkyl groups and donor solvent on the reactivity of 1-3 is briefly discussed.
THERMODINAMYCS OF THE ISODESMIC ENOL-TO-METHYL ENOL ETHER EQUILIBRIUM IN WATER
Toullec, Jean,El-Alaoui, Mohiedine,Kleffert, Pascal
, p. 1889 - 1892 (2007/10/02)
ΔGo values for the isodesmic equilibrium between substituted acetophenone enols and corresponding methyl enol ethers are calculated from previously reported data on equilibrium constants for keto-enol tautomerism and for enol ether formation from ketones.These values agree with those expected from literature data on analogous alcohol-ether isodesmic systems.
Carbonyl Methylenation Using a Titanium- Aluminum (Tebbe) Complex
Pine, Stanley H.,Pettit, Robert J.,Geib, Gregory D.,Cruz, Susana G.,Gallego, Claudio H.,et al.
, p. 1212 - 1216 (2007/10/02)
The titanium-aluminum (Tebbe) complex is shown to be an effective methylenating agent for a variety of carbonyl groups.The reaction is unique in that the carbonyl groups of carboxylic acid derivatives are readily methylenated.Thus vinyl enol ethers are prepared from esters and enamines are formed from amides.The complex provides a method for methylenating hindered or base sensitive ketones that is advantageous to the Wittig reagent.Selective methylenation of dicarbonyl compounds is also accomplished.
The Allopolarization Principle and its Applications, IV. Substituent Effects in the Methylation of Enolate Anions
Gompper, Rudolf,Vogt, Hans-Hubert
, p. 2866 - 2883 (2007/10/02)
The ratio of O- and C-methylated products in the reaction of the sodium salts of acetophenones 1, propiophenones 3, phenylacetones 5, β-dicarbonyl compounds 12, α-cyanocarbonyl compounds 13, acetaldehyde, propionaldehyde, and diethylketone with dimethyl sulfate, methyl iodide, and trimethyl phosphate in HMPTA has been determined with regard to the effect of substituents.In some cases the influence of solvents, concentration and temperature has also been studied.
