Alkenes In Aqueous Media Research Articles

Bis-NHC–Ag/Pd(OAc)2 Catalytic System Catalyzed Transfer Hydrogenation Reaction

The bis-NHC–Ag/Pd(OAc)2 catalytic system (NHC = N-heterocyclic carbene), a combination of bis-NHC–Ag complex and Pd(OAc)2, was found to be a smart catalyst in the Pd-catalyzed transfer hydrogenation of various functionalized arenes and internal/terminal alkynes. The catalytic system demonstrated high efficiency for the reduction of a wide range of various functional groups such as carbonyls, alkynes, olefins, and nitro groups in good to excellent yields and high chemoselectivity for the reduction of functional groups. In addition, the protocol was successfully exploited to stereoselectivity for the transformation of alkynes to alkenes in aqueous media under air. This methodology successfully provided an alternative useful protocol for reducing various functional groups and a simple operational protocol for transfer hydrogenation.

A Simple and Efficient Procedure for Rh(I)‐ and Ir(I)‐complex Catalyzed Para‐hydrogenation of Alkynes and Alkenes in Aqueous Media Resulting in Strong PHIP Effects

AbstractCatalytic hydrogenations with para‐H2 may lead to strong para‐hydrogen induced polarization (PHIP) and the hyperpolarized probe molecules may enable the application of the Magnetic Resonance Imaging (MRI) diagnostic modality for metabolism imaging. The use of water as a solvent for para‐hydrogenation reactions is very challenging due to the fast exchange between the catalytically active metal hydrides and the water protons and also because of the low hydrogen solubility in water. Here we report that several water‐soluble Rh(I)‐ and Ir(I)‐complexes with N‐heterocyclic carbene (NHC) and/or tertiary phosphine ligands efficiently catalyze the synthesis of hyperpolarized compounds by para‐hydrogenation in aqueous media.

Rhodium-catalyzed aminohydroxylation of unactivated alkenes in aqueous media for the benign synthesis of 1,2-amino alcohols

An efficient catalytic aminohydroxylation reaction of alkenes in aqueous media is disclosed for the first time.

An efficient ultrasound-promoted method for the synthesis of bis(indole) derivatives

In this paper, the reaction of indole with electron-deficient alkenes in aqueous media is reported. This procedure allows the synthesis of bis(indole) derivatives in good to high yields at 90 °C under silent and ultrasound irradiation conditions. Short reaction times and high yields of desired products are the main advantages of the presented procedure. This reaction catalyzed by 12-tungstophosphoric acid is operationally simple and considers environmental aspects by avoiding toxic catalysts and solvents.

Direct sustainable bromination of alkenes in aqueous media and basic ionic liquids

Electron-rich and electron-poor alkenes have been dibrominated using a rapid and sustainable procedure. The reactions were conducted in aqueous medium and basic ionic liquids which catalyzed the direct addition of bromine. The protocol leads to remarkable results, high yields under mild conditions, complete chemo- and stereo-selectivity and allows the recycling of ionic liquids, reducing costs, and environmental impact.

Reactions of gold(III) complexes with alkenes in aqueous media: generation of bis-(β-hydroxyalkyl)gold(III) complexes

Reactions of gold(III) complexes with ethylene and propylene in water provide the first such examples not accompanied by reduction of the gold. HAuCl4 and AuCl3(TPPTS) produce organic products (alcohol, aldehyde/ketone, etc.) with gold reduction to the metal. However, [Au(bipy)Cl2]Cl in water produces the gold(III) β-hydroxy complexes, [Au(bipy)(CH2CH2OH)2]X (X = Cl−, PF6 −) and [Au(bipy)(CH2CH(OH)CH3]Cl, which are stable in solution. These complexes could not be isolated, but were characterized by NMR and high-resolution mass spectra. [Au(terpy)Cl]Cl2 fails to react with ethylene in water, even at elevated temperatures. DFT computations were performed to investigate the reaction mechanism.

Genomic salmon testes DNA as a catalyst for Michael reactions in water

The DNA molecule, recognized as the carrier of genetic information in vivo, can function as an efficient organocatalyst for Michael additions of 1,3-dicarbonyl compounds to activated alkenes in aqueous media. The procedure described here is environmentally benign and offers several advantages in terms of simplicity, generality and efficiency. We have used fluorescence spectroscopy to evaluate the catalytic activity of a molecule of DNA.

Zn/RuCl3‐Promoted Cleavage of Diselenides: An Efficient Michael Addition of Zinc Selenolates to Conjugated Alkenes in Aqueous Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Zn/RuCl3-Promoted Cleavage of Diselenides: An Efficient Michael Addition of Zinc Selenolates to Conjugated Alkenes in Aqueous Media

A simple and highly efficient one-pot route to β-selenocarbonyl compounds and nitriles has been developed by Zn/RuCl3-catalyzed cleavage of diselenides and subsequent Michael addition of zinc selenolates to conjugated alkenes in aqueous media.

Mono‐ and β,β‐Double‐Heck Reactions of α,β‐Unsaturated Carbonyl Compounds in Aqueous Media.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A chemoenzymic approach to the epoxidation of alkenes in aqueous media

Hydrogen peroxide, generated insitu by the enzymic oxidation of glucose using glucose oxidase, is coupled to a catalytic system of sodium bicarbonate/manganese sulfate to epoxidize alkenes in aqueous media.

Mono- and β,β-Double-Heck Reactions of α,β-Unsaturated Carbonyl Compounds in Aqueous Media

Optimized reaction conditions for the mono- and beta,beta-diarylation of electron-deficient alkenes in aqueous media catalyzed either by a p-hydroxyacetophenone oxime-derived palladacycle or by palladium(II) acetate under phosphine-free conditions and in the presence of (dicyclohexyl)methylamine as base are described. Regioselective monoarylation of unsubstituted and substituted alpha,beta-unsaturated carbonyl compounds takes place with aryl iodides at 120 degrees C in water. Aqueous N,N-dimethylacetamide (DMA), tetra-n-butylammonium bromide (TBAB) as additive, and the palladacycle as catalyst are the most efficient conditions for the coupling with aryl bromides, good stereoselectivities being also obtained in the arylation of crotonates and itaconates, whereas cinnamic derivatives afford lower steroselectivity, with the exception of cinnamic acid and nitrile. beta,beta-Diarylation of unsubstituted alpha,beta-unsaturated carbonyl compounds can be controlled by using higher loading of the palladacycle and can be performed in refluxing water for aryl iodides, whereas DMA must be used for aryl bromides. Microwave irradiation can be used in the monoarylation of tert-butyl acrylate with aryl iodides in water or the coupling between ethyl cinnamate and aryl bromides in aqueous DMA.

N‐Ethylpiperidine Hypophosphite Mediated Intermolecular Radical Carbon—Carbon Bond Forming Reaction in Water.

AbstractFor Abstract see ChemInform Abstract in Full Text.

ChemInform Abstract: A Radical Carbon—Carbon Bond Forming Reaction: Indium‐Mediated Radical Addition to β‐Substituted Conjugated Alkenes in Aqueous Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Radical Carbon-carbon Bond Forming Reaction: Indium Mediated Radical Addition to β-Substituted Conjugated Alkenes in Aqueous Media

Indium-mediated 1,4-addition of alkyl radical to β-substituted conjugated alkenes in aqueous media has been developed. The reaction affords 1,4-addition products to various α,β-enones regiospecifically in high isolated yields.

N-Ethylpiperidine Hypophosphite Mediated Intermolecular Radical Carbon-Carbon Bond Forming Reaction in Water

N-Ethylpiperidine hypophosphite mediated radical addition reactions to electron deficient alkenes in aqueous media have been developed. The reactions afford high isolated yields of addition products without using a large excess of alkenes.

Tuning the Catalytic Activity of Cyclodextrin-Modified Palladium Nanoparticles through Host−Guest Binding Interactions

Water-soluble Pd nanoparticles (diameter 3.5 ± 1.0 nm) modified with covalently-attached cyclodextrin (CD) receptors were prepared by the reduction of PdCl42- in dimethylformamide solution containing perthiolated β-CD. These Pd nanoparticles behave as active catalysts for the hydrogenation of alkenes in aqueous media. For instance, the turnover frequency for the hydrogenation of 1-butenyltrimethylammonium bromide (1) was found to be 320 (moles of 1) (moles of Pd)-1 h-1 at 25 °C and 1.0 atm of H2(g). The addition of cationic ferrocene derivatives, such as ferrocenylmethyltrimethylammonium bromide (3), to the reaction medium decreases the catalytic activity of the Pd nanoparticles. Other CD substrates, such as anionic ferrocene derivatives or neutral adamantanol, are much less effective as inhibitors of the catalytic hydrogenation process.

ChemInform Abstract: Conjugated Addition Reactions of Nitroalkanes with Electrophilic Alkenes in Aqueous Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Conjugated Addition Reactions of Nitroalkanes with Electrophilic Alkenes in Aqueous Media

The Michael reaction of various nitroalkanes 1 with electrophilic alkenes 2 can be performed in NaOH (0.025−0.1 M), without any organic solvent. In many cases the presence of cetyltrimethylammonium chloride (CTACl), as cationic surfactant, produces better results. Good yields of the products 3 are obtained even with hindered, and functionalized starting materials.

Selective electrocatalysis of alkenes in aqueous media. A comparison of reactivities for oxoferryl porphyrin and oxoferryl porphyrin radical cation at room temperature

A stable high-valent oxoferryl porphyrin radical cation is electrochemically generated in aqueous media at room temperature which rapidly catalyses the oxidation of alkenes to give eneones and diols; by contrast the oxoferryl porphyrin only slowly catalyses oxidation and gives only the eneone.