Even in the context of hydrocarbons' general resistance to selective functionalization, methane's volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze reaction methane (CH(4)) with ethyl diazoacetate (N(2)CHCO(2)Et) yield propionate (CH(3)CH(2)CO(2)Et). The use supercritical carbon dioxide (scCO(2)) as solvent is key reaction's success. Although catalyst only sparingly soluble CH(4)/CO(2)...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRegioselective oxyfunctionalization of unactivated tertiary and secondary carbon-hydrogen bonds alkylamines by methyl(trifluoromethyl)dioxirane in acid mediumGregorio Asensio, Maria Elena Gonzalez-Nunez, Carmen Boix Bernardini, Rossella Mello, Waldemar AdamCite this: J. Am. Chem. Soc. 1993, 115, 16, 7250–7253Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue 1 August...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermally and photochemically initiated radical chain decomposition of ketone-free methyl(trifluoromethyl)dioxiraneWaldemar Adam, Ruggero Curci, Maria Elena Gonzalez Nunez, Rossella MelloCite this: J. Am. Chem. Soc. 1991, 113, 20, 7654–7658Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September...

Supercritical carbon dioxide (scCO2) is an effective reaction medium to perform the oxidation of primary and secondary aliphatic alcohols corresponding carbonyl compounds with chromium trioxide supported on silica. These reactions were performed by flowing a solution alcohol in scCO2 through column containing reagent recovering product depressurization. This method avoids use organic solvents contamination products species.

Formylation d'alcools aliphatiques, terpeniques, monocycliques, benzyliques, allyliques et steroidiques a l'aide du reactif de Vilsmeier (forme partir chlorure benzoyle DMF)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEpoxidation of Primary and Secondary Alkenylammonium Salts with Dimethyldioxirane, Methyl(trifluoromethyl)dioxirane, m-Chloroperbenzoic Acid. A General Synthetic Route to EpoxyalkylaminesGregorio Asensio, Rossella Mello, Carmen Boix-Bernardini, Maria Elena Gonzalez-Nunez, Gloria CastellanoCite this: J. Org. Chem. 1995, 60, 12, 3692–3699Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June...

A general method for the synthesis of N,O-aminals derived from primary aromatic amines is described. The reactivity these compounds under neutral and acidic conditions has been studied title can be envisaged as purpose H2CNAr or (H2CNHAr)+ equivalents. N,O-Aminals have converted into perhydrotriazines by moderate heating bis(4-aminoaryl)methane derivatives N-benzylarylamines, respectively when heated in media with pH control. Reduction N,O-acetals sodium cyanoborohydride revealed that C–O...

Anhydrous [2-percarboxyethyl] functionalized silica (2a) is an advantageous oxidant for performing the epoxidation of olefins 1. Epoxides 3 do not undergo ring-opening reactions catalyzed by acidic surface, except particularly activated cases such as styrene oxide. The hydrophilic and character surface does interfere with directing effects exerted allylic H-bond acceptor substituents. alkenes 1 carrying hydroxyl groups react silica-supported peracid 2a faster than unsubstituted alkenes, thus...

Abstract The development of catalytic methods for the effective functionalization methane yet remains a challenge. best system known to date is so‐called Catalytica Process based on use platinum catalysts convert into methyl bisulfate with TOF rate 10 −3 s. In this contribution, we report series silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze ethyl propionate upon reaction diazoacetate (EDA) by using supercritical carbon dioxide (scCO 2 ) as medium....

Reactions of hydrogen peroxide with several lacunary polyoxometalates the 1:11 series, XW11O39m- (X = Co3+, Ga3+, Fe3+, Si4+, and P5+), are reported. Synthetic pathways to new polyoxotungstates incorporating dioxygen moieties (peroxo and/or superoxo) developed. The key step involves treating precursors H2O2 in strongly buffered aqueous solutions. Upon reaction α-[Co3+W11O39],9- (a) central tetrahedral Co3+ is reduced Co2+ (b) each four unshared oxygens surrounding vacancy replaced by a...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxygen atom insertion into the benzylic carbon-hydrogen bond of (R)-(-)-2-phenylbutane by methyl(trifluoromethyl)dioxirane: an efficient and mild regio- stereoselective synthesis (S)-(-)-2-phenyl-2-butanolWaldemar Adam, Gregorio Asensio, Ruggero Curci, Maria Elena Gonzalez-Nunez, Rossella MelloCite this: J. Org. Chem. 1992, 57, 3, 953–955Publication Date (Print):January 1, 1992Publication History Published online1 May 2002Published inissue 1...

Earlier studies established that dimethyldioxirane (1a) reacts with sulfides 2 in two consecutive concerted electrophilic oxygen-transfer steps to give first sulfoxides 3 and then sulfones 4. The same sequential oxidation model was assumed for the reaction of strongly methyl(trifluoromethyl)dioxirane (1b). In this paper we report on a systematic general study mechanism simple DMDO TFDO (1b) which provides clear evidence involvement hypervalent sulfur species process. 2a−c, diphenyl sulfide...

[reaction: see text] Potassium peroxomonosulfate deposited onto silica SiO2 x KHSO5 efficiently reacts with ketones in dichloromethane at room temperature to give the corresponding esters or lactones quantitative yields. This method avoids hydrolysis of reaction products. The Baeyer-Villiger is catalyzed by potassium hydrogensulfate present supported reagent.

[2-Percarboxyethyl]-functionalized silica reacts with ketones in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions to yield the corresponding esters lactones. The solid reagent can be easily recycled through treatment 70% hydrogen peroxide presence of an acid 0 °C. This procedure not only simplifies isolation reaction products, but has advantage using water as solvents mild conditions.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOne-electron reduction of methyl(trifluoromethyl)dioxirane by iodide ion. Evidence for an electron-transfer chain reaction mediated the superoxide ionWaldemar Adam, Gregorio Asensio, Ruggero Curci, Maria Elena Gonzalez-Nunez, and Rossella MelloCite this: J. Am. Chem. Soc. 1992, 114, 22, 8345–8349Publication Date (Print):October 1, 1992Publication History Published online1 May 2002Published inissue 1 October...

Supercritical carbon dioxide (scCO2) is an efficient reaction medium to perform the Baeyer-Villiger oxidation with hydrated silica-supported potassium peroxomonosulfate (h-SiO2.KHSO5) under flow-through conditions. Hydration modulates reactivity of active surface by softening acidity KHSO4 present in supported reagent. The scCO2 much more than n-hexane similar conditions, which attributed better transport and solvating properties supercritical regard n-hexane.

1,1,1-Trifluoroacetone (2a) reacts as a hydride-acceptor in the Oppenauer oxidation of secondary alcohols (1) presence diethylethoxyaluminum. The oxidant allows for selective primary alcohols.

Abstract Supercritical carbon dioxide is a convenient medium for performing the selective oxidation of sulfides 1 to either sulfoxides 2 or sulfones 3 with [2‐percarboxyethyl]‐functionalized silica ( 4 ) under flow conditions. The chemoselectivity reaction, which results from different diffusion rates sulfide and sulfoxide over reagent bed, can be controlled by adjusting pressure hydration surface as both solvating power mobile phase activity stationary determine migration supported...

The oxidation of lineal, cyclic, and bicyclic aliphatic p-chlorobenzoic p-chorobenzenesulfonic acid esters 2 with methyl(trifluoromethyl)dioxirane (TFDO) (1) occurs at positions in the hydrocarbon chain distant from directing group a significant degree selectivity to give corresponding keto or hydroxy esters. Compounds are relatively deactivated respect this due electron-withdrawing nature ester moiety. Methylene Cα−H Cβ−H bonds remain unchanged all cases, but tertiary undergo TFDO (1)....

Anhydrous 2-percarboxyethyl-functionalized silica (2b), a recyclable supported peracid, is suitable reagent to perform the epoxidation of alkenes 1 in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions. This procedure simplifies isolation reaction products uses only as solvent mild The solid 2b can be easily recycled by with 30% hydrogen peroxide an acid medium.

The oxidation of iodomethane with dimethyldioxirane allows the generation stable neutral solutions hypoiodous acid in absence any trapping agent for iodide anion. Hypoiodous is trapped situ by addition to representative olefins give iodohydrines good yields. stereochemical study products shows anti-stereospecific nature iodohydroxylation reaction.

The reactivity of individual C--H bonds in the methyl(trifluoromethyl)dioxirane TFDO oxygenation stereogenic methylene groups conformationally homogeneous monosubstituted cyclohexanes (2) has been determined. unexpectedly high occurrence O-atom insertion into C--H(ax) suggests an plane trajectory attack while diastereoselectivity reaction is qualitatively interpreted on basis distinct hyperconjugative stabilization by substituent diastereomeric transition states due to long-range through...