Air-stable Catalyst Research Articles

Direct Conversion of Carbohydrates into 5‐Ethoxymethylfurfural (EMF) and 5‐Hydroxymethylfurfural (HMF) catalyzed by Oxomolybdenum complexes

AbstractThis work reports the first methodology for one‐pot synthesis of 5‐ethoxymethylfurfural (EMF) and 5‐hydroxymethylfurfural (HMF) from various carbohydrates catalyzed by oxo‐molybdenum complexes. The best results of EMF (53‐60 %) were obtained using a mixture of ethanol/THF (5:2) catalyzed by MoO2Cl2(H2O)2 at 120 °C, after 17 h. This dioxo‐molybdenum complex also promoted the synthesis of EMF from other carbohydrates such as inulin and sucrose. The selective conversion of fructose into HMF was achieved in good yield (75 %) from fructose using MoO2Cl2(H2O)2 in DMSO at 120 °C after 30 minutes. This novel methodology has the advantages of using an inexpensive, environmental friendly and air stable catalyst with an easy preparation.

Direct Catalytic Alcoholysis of Unactivated 8-Aminoquinoline Amides

Direct catalytic alcoholysis of unactivated amides is one of the most difficult challenges in organic chemistry, and an applicable method for cleaving amides used as directing groups in regioselective functionalization reactions has not been reported. Herein, we report direct catalytic alcoholysis of 8-aminoquinoline amides, which are highly effective directing groups in regioselective functionalization reactions. The reactions proceeded with a simple combination of substrates, air-stable catalysts, and alcohols, affording the corresponding esters in good yields with broad functional group tolerance. Highly chemoselective cleavage of the 8-aminoquinoline amides in the presence of related carbonyl functionalities and preliminary mechanistic studies are also described.

Ru(II)-Catalyzed C-H Functionalization on Maleimides with Electrophiles: A Demonstration of Umpolung Strategy.

The unconventional nucleophilic reactivity of maleimides, innate electrophiles, has been realized under Ru(II)-catalysis such that exposure to electrophiles delivered products of C-H chalcogenation and amidation in good yields (up to 94%). This protocol features mild conditions and operational simplicity with broad substrate scope, uses an inexpensive and air-stable catalyst, and also represents the first example of Ru(II) catalyzed C-H selenylation of alkenes.

Iron‐Mediated Desulphurization Towards the Synthesis of 2‐Halo Aromatic Isothiocyanates

AbstractA highly efficient and simple protocol for the construction of 2‐haloaromatic isothiocyanates from their respective amines in the presence of cheap, readily available and air stable iron catalyst is described. All the reactions were carried out under moderate reaction conditions could give their target products in good to excellent yields in shorter reaction time

Copper promoted desulfurization towards the synthesis of isothiocyanates

The cheap, readily available and air stable catalyst was used as the desulfurization agent for the conversion of aniline to isothiocyanates in one pot two step reaction under mild reaction conditions.

An efficient methodology for the synthesis of thioureas from amine mediated by a cobalt source

The cheap, readily available and air stable cobalt catalyst was used as the desulfurization agent for the conversion of aniline to thioureas in one pot three step reaction under mild reaction conditions. The reactions are rapid and facile and accomplished at room temperature.

Palladium catalyzed direct coupling of 5-bromo-2-furaldehyde with furfural and thiophene derivatives

A direct coupling approach for the synthesis of 5,5′-bisfurfural via the coupling of 2-furaldehyde (furfural) and 5-bromo-2-furaldehyde using the air-stable catalyst Pd(OAc)2 and the air-stable ligand P(t-Bu)3HBF4 was examined. The developed procedure was used to functionalize thiophene containing moieties commonly found in organic electronics. The aromatic CH bond activated coupling with 5-bromo-2-furaldehyde afforded novel compounds with useful 5-heteroaryl-2-furaldehyde type functionality.

Cobalt mediated by desulfurization toward the synthesis of isothiocyanates

ABSTRACTA highly efficient and simple protocol for the construction of aromatic and aliphatic isothiocyanates from their respective amines in the presence of cheap, readily available, and air-stable cobalt catalyst is described. All reactions were carried out under optimized reaction conditions and gave target products in good to excellent yields within shorter reaction time.

Reactivity of 1-(2-bromobenzyl)-4-halopyrazoles in intermolecular and intramolecular Pd-catalysed direct arylations

The reactivity of 1-(2-bromobenzyl)-4-halopyrazoles in inter- and intra-molecular Pd-catalysed direct arylation was investigated. Conditions allowing the intermolecular C5-arylations of both 1-(2-bromobenzyl)-4-chloropyrazoles and 1-(2-bromobenzyl)-4-bromopyrazoles, without cleavage of the pyrazolyl and benzyl C-halo bonds, are reported. Using KOAc as the base, DMA as the solvent and 2 mol% of an air stable palladium catalyst, the target C5-arylated pyrazoles were obtained in moderate to good yields with a wide variety of aryl bromides. The synthesis of 3-halopyrazolo[5,1-a]isoindoles via intramolecular Pd-catalysed direct arylation, without cleavage of the pyrazolyl C-halo bonds is also described. Moreover, sequential Pd-catalysed C5-arylations followed by intramolecular direct arylation allowed the access to dibenzo[c,e]pyrazolo[1,5-a]azepine derivatives. The reactivity of the 2-bromobenzyl moiety of C5-arylated 1-(2-bromobenzyl)-4-halopyrazoles in intermolecular direct arylation or in Suzuki coupling is also described.

ChemInform Abstract: Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes.

AbstractThe novel method is advantageous with regards to operational simplicity and use of an inexpensive, environmentally friendly air stable catalyst.

Novel Cu(0)–Fe3O4@SiO2/NH2cel as an Efficient and Sustainable Magnetic Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-triazoles and 2-Substituted-Benzothiazoles via One-Pot Strategy in Aqueous Media

A novel, air stable, water dispersible and efficient magnetic catalyst based on copper nanoparticles onto ethylene diamine functionalized inorganic/organic composite [Cu(0)–Fe3O4@SiO2/NH2cel] has been prepared. Functionalization of inorganic/organic composite by ethylene diamine imparts desirable chemical functionality and enables the generation of active sites for the immobilization of Cu(0) nanoparticles. The novel catalyst system has been well characterized by various techniques like FTIR, TGA, XRD, SEM, HRTEM, EDX, ICP-AES, UV–Vis and VSM. Further, Cu(0)–Fe3O4@SiO2/NH2cel opens up a new avenue to introduce a very useful and efficient catalytic system for the one-pot synthesis of 1,4-disubstituted-1,2,3-triazoles via 1,3-dipolar cycloaddition of terminal acetylenes to azides, generated in situ from anilines in water at room temperature, and one-pot three component reaction of 2-iodoaniline, aldehyde and thiourea as sulphur source for the synthesis of 2-substituted-benzothiazole derivatives in water. The novel heterogeneous magnetic catalyst offers recyclability without significant deterioration in catalytic activity and can be easily recovered using an external magnet, thus making it eco-friendly and economical to perform the desired transformations.

ChemInform Abstract: CaII‐Catalyzed Alkenylation of Alcohols with Vinylboronic Acids.

AbstractAlkenylation of alcohols with vinylboronic acids is readily achieved in generally moderate to good yields using Ca(NTf2)2 as an air stable catalyst.

ChemInform Abstract: Chemoselective Carbene Insertion into the N—H Bond over O—H Bond Using a Well‐Defined Single Site (P—P)Cu(I) Catalyst.

AbstractThe air‐stable catalyst renders possible the desired chemoselective insertion and avoids formation of olefinic products.

Molybdenum hexacarbonyl: air stable catalyst for microwave assisted intermolecular [2+2+2] co-trimerization involving propargyl halides

Intermolecular [2+2+2] cycloaddition of propargyl halides with 1,6-diynes was achieved with air stable, catalytic amount of Mo(CO)6 and the benzyl halide derivatives were isolated in good yields. The reaction conditions were optimized and better yields were observed under microwave irradiation conditions using acetonitrile as a solvent.

A Simple and Efficient Palladium Catalyst of Nitrogen-Based Ligand for Cu(I)- and Amine-Free Sonogashira Reaction

Glycine, as a kind of commercially available and inexpensive ligand, is used to prepare an air-stable and water-soluble catalyst used in Sonogashira reaction in our study. In the presence of 1% [PdCl2(NH2CH2COOH)2] as catalyst, excellent catalytic activity towards the Sonogashira coupling of aryl iodides with terminal alkynes without using any additive such as Cu(I)-cocatalyst is observed in a mixture of water and acetone (3/3 mL) under air at 60 °C with NaOH as a base, giving products in good to excellent yields.

Copper-Catalyzed Synthesis of Weinreb Amides by Oxidative Amidation of Alcohols

A simple and efficient protocol has been developed for the oxidative amidation of alcohols to Weinreb amides using tert-butyl hydroperoxide as an oxidant and an inexpensive and air stable copper catalyst. The present protocol is advantageous as it uses commercially affordable alcohols as starting materials. The developed protocol also tolerates various substituted alcohols as starting materials to provide good to excellent yields of the desired products.

Copper Nanoparticles Supported on Agarose as a Bioorganic and Degradable Polymer for Multicomponent Click Synthesis of 1,2,3-Triazoles under Low Copper Loading in Water

Agarose-supported copper nanoparticles (CuNPs@agarose) were prepared by immobilization of copper bromide on agarose followed by in situ chemical reduction. The new material was characterized by SEM, EDX, TEM, TGA, XRD, nitrogen adsorption–desorption, and solid UV–vis analysis. The catalytic activity of CuNPs@agarose was assessed in the three component click synthesis of 1,2,3-triazoles in water under low catalyst loading and mild reaction conditions. The easy synthesis and air-stable catalyst was recycled for five runs with small drops in catalytic activity.

Hydroformylation of Styrene, Vinyl Acetate and Allyl Cyanide with Air-Stable Rhodium Catalysts Ligated by C2-Symmetric bis-N-Heterocyclic Carbenes

Hydroformylation of Styrene, Vinyl Acetate and Allyl Cyanide with Air-Stable Rhodium Catalysts Ligated by C2-Symmetric bis-N-Heterocyclic Carbenes

Palladium nanoparticles supported on agarose-functionalized magnetic nanoparticles of Fe3O4 as a recyclable catalyst for C–C bond formation via Suzuki–Miyaura, Heck–Mizoroki and Sonogashira–Hagihara coupling reactions

Palladium nanoparticles supported on agarose functionalized Fe3O4 catalyzed C–C bond formation reactions.

Complex of 2-(methylthio)aniline with palladium(II) as an efficient catalyst for Suzuki–Miyaura C[sbnd]C coupling in eco-friendly water

2-(Methylthio)aniline (L1), a bidentate (S,N) ligand synthesized by the reaction of o-aminothiophenol with methyl iodide, on reacting with Na2PdCl4 in acetone and water gives a complex [PdL1Cl2] (1). Single crystal X-ray diffraction studies have revealed that the geometry of palladium in 1 is nearly square-planar and the ligand L1 is bound to the palladium through S and N in a bidentate coordination mode forming a five membered chelate ring. This complex functions as a thermally and air stable catalyst of high efficiency for Suzuki–Miyaura CC coupling reactions in water. It catalyzes CC coupling between various aryl bromides and phenylboronic acid under mild reaction conditions in water. TON value up to 93,000 has been obtained.