Nano indium oxide catalyzed efficient synthesis of propargylamines via C-H and C-Cl bond activations

A simple, and efficient nano In₂O₃ catalyzed one-pot three-component coupling of terminal alkyne, dichloromethane, and secondary amine has been developed for the synthesis of propargylamines under mild reaction conditions. The catalyst was recovered and reused for three times without significant loss of catalytic activity.     

An efficient synthesis of propargylamines via three-component coupling of aldehydes, amines and alkynes catalyzed by nanocrystalline copper(II) oxide

An efficient three-component coupling of aldehydes, amines and alkynes to prepare propargylamines, in nearly quantitative yields using nanocrystalline CuO as a catalyst is described. Structurally divergent aldehydes and amines were converted to the corresponding propargylamines. The reaction does not require any co-catalyst. After completion of the reaction, the catalyst was recovered by centrifugation and reused several times with only a slight decrease of activity observed under the same reaction conditions.     

Very mild, enantioselective synthesis of propargylamines catalyzed by copper(I)-bisimine complexes

The stereoselective addition of aryl- and alkylacetylene derivatives to imines was studied. The reaction is catalyzed by copper complexes of enantiomerically pure bisimines, readily prepared in very high yields from the commercially available binaphthyl diamine. A very simple experimental procedure allowed to obtain at room temperature optically active propargylamines in high yields and enantioselectivity. Interestingly, bisimine/copper(I) complexes were able to promote the direct, enantioselective, catalytic addition to imines of alkylacetylenes. The effects of catalyst loading and other reaction parameters on the stereochemical outcome of the transformation were investigated. The extremely convenient methodology, the mild reaction conditions, and the possibility of a modular approach for developing new and more efficient bisimine-based chiral ligands make the present methodology very attractive.     

An efficient and facile one-pot synthesis of propargylamines by three-component coupling of aldehydes, amines, and alkynes via C-H activation catalyzed by NiCl2

NiCl₂ was found to be a highly efficient and effective catalyst for the one-pot three-component (A³) coupling of aldehydes, amines, and alkynes to produce propargylamines in nearly quantitative yields. Structurally divergent aldehydes, amines, and alkynes were converted into the corresponding propargylamines. No co-catalyst or activator is needed and water is the only byproduct of this novel protocol.     

Mononuclear rearrangement of heterocycles in ionic liquids catalyzed by copper(II) salts

The reactivity of E- and Z-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole in the presence of CuCl₂ and Cu(ClO₄)₂·6H₂O has been studied in four imidazolium ionic liquids [bmim][X] (X=BF₄⁻, PF₆⁻, SbF₆⁻ and CF₃SO₃⁻). The reaction may follow different mechanistic patterns, depending on the nature of the ionic liquid anion, accounting for both qualitative and kinetic data. In the presence of CuCl₂, two processes take place at the same time, i.e., the E?Z isomerization and the rearrangement of Z-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole. In contrast, in the presence of Cu(ClO₄)₂·6H₂O, the rearrangement occurs only in solution of [bmim][BF₄] and [bmim][CF₃SO₃]. Collected data show that the effect of the ionic liquid on the isomerization and the rearrangement is different. In particular, a higher cross-linking degree seems to favour the triazole, but disfavour the E?Z isomerization.     

Asymmetric multicomponent copper catalyzed synthesis of chiral propargylamines

A three-component stereoselective reaction between an aldehyde, an amine and phenylacetylene to afford optically active propargyl amines in good yields was developed. The reaction is catalysed by copper complexes of enantiomerically pure bis-imines. The best results were obtained with imines readily prepared in very high yields from the commercially available binaphtyl diamine.

A very simple experimental procedure at room temperature allowed to obtain optically active propargyl amines in very good yields and enantioselectivity up to 75%. The extremely simple methodology and the mild reaction conditions, as well as the possibility of a modular approach for developing new and more efficient bis-imine-based chiral ligands make the present methodology very attractive.     

Highly efficient C-H insertion reactions of hydrogen peroxide catalyzed by homogeneous and heterogeneous methyltrioxorhenium systems in ionic liquids

A convenient and efficient C-H insertion reaction of environment friendly H₂O₂ into representative hydrocarbon derivatives by homogeneous methyltrioxorhenium (MTO), heterogeneous poly(4-vinylpyridine)/methyltrioxorhenium (PVP/MTO) and microencapsulated polystyrene/methyltrioxorhenium (PS/MTO) systems in ionic liquids, is described. In some cases a higher activity was observed if compared with the same reaction in molecular solvents. The heterogeneous catalysts are stable systems under the reaction conditions and can be recycled for more transformations.     

Highly efficient synthesis of amides via Ritter chemistry with ionic liquids

The utility of Brønsted-acidic imidazolium ionic liquid [BMIM(SO₃H)][OTf] as catalyst for the high yield synthesis of a wide variety of amides under mild conditions via the Ritter reaction of alcohols with nitriles has been demonstrated. As alternative methods for the carbocation generation step, NOPF₆ immobilized in [BMIM][PF₆] ionic liquid was used in the Ritter reaction of bromides with nitriles and for the synthesis of adamantyl amides from adamantane and nitriles.     

Rhodium catalyzed synthesis of isoindolinones via C-H activation of N-benzoylsulfonamides

An efficient approach to a wide range of isoindolinones, including 3-monosubstituted and 3,3-disubstituted isoindolinones, from the annulation of N-benzoylsulfonamides with olefins and diazoacetate has been developed. The transformation is broadly compatible with both terminal and internal olefins. Moreover, diazoacetate is for the first time incorporated into an amide-directed C-H functionalization reaction. Specifically, the rhodium complex [{RhCl₂Cp*}₂] enables the in situ dimerization of diazoacetate in addition to its role in catalyzing C-H functionalization/cross-coupling.     

An efficient Ullmann-type C-O bond formation catalyzed by an air-stable copper(I)-bipyridyl complex

An efficient O-arylation of phenols and aliphatic alcohols with aryl halides was developed that uses an air-stable copper(I) complex as the catalyst. This arylation reaction can be performed in good yield in the absence of Cs2CO3. A variety of functional groups are compatible with these reaction conditions with low catalyst loading levels.     

Glycolysis of poly(ethylene terephthalate) catalyzed by ionic liquids

Poly(ethylene terephthalate) (PET) from an industrial manufacturer was depolymerized by ethylene glycol in the presence of a novel catalyst: ionic liquids. It was found that the purification process of the products in the glycolysis catalyzed by ionic liquids was simpler than that catalyzed by traditional compounds, such as metal acetate. Qualitative analysis showed that the main product in the glycolysis process was the bis(hydroxyethyl) terephthalate (BHET) monomer. Thermal analysis of the glycolysis products was carried out by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The influences of experimental parameters, such as the amount of catalyst, glycolysis time, reaction temperature, and water content in the catalyst on the conversion of PET, selectivity of BHET, and distribution of the products were investigated. Results show that reaction temperature is a critical factor in this process. In addition, a detailed reaction mechanism of the glycolysis of PET was proposed.     

Diastereoselective synthesis of propargylamines catalyzed by Cu-MCM-41

In this work, a rapid, efficient and protecting group free diastereoselective synthesis of propargylamines through a multicomponent coupling reaction between (S)-prolinol, phenylacetylene and commercially available aldehydes catalyzed by Cu-MCM-41 in heterogeneous phase is reported. The reactions were carried out under solvent free conditions with good yields and moderate reaction times. In all the cases, catalyst was recovered and reused up to five cycles. Recyclability of the catalyst, low catalyst loading, solvent and protecting group free conditions, and the use of inexpensive catalyst are the key features that provide green aspects to this synthetic protocol.     

Microwave-promoted three-component coupling of aldehyde, alkyne, and amine via C-H activation catalyzed by copper in water

[reaction: see text] An efficient three-component coupling of aldehyde, alkyne, and amine to generate propargylamines has been effected under microwave irradiation in water using only CuI catalyst without the noble metal cocatalyst. This method has proved to be applicable to a wide range of substrates. In addition, the preliminary experiment using (S)-proline methyl ester as a chiral source demonstrated that it could be developed to be a direct and highly diastereoselective method for construction of chiral propargylamines.     

Dimethyl carbonate synthesis catalyzed by DABCO-derived basic ionic liquids via transesterification of ethylene carbonate with methanol

Easily prepared DABCO-derived (1,4-diazobicyclo[2.2.2]octane) basic ionic liquids were developed for an efficient synthesis of dimethyl carbonate (DMC) via the transesterification of ethylene carbonate (EC) with methanol. 1-Butyl-4-azo-1-azoniabicyclo[2.2.2]octane hydroxide ([C₄DABCO]OH) exhibited high catalytic activity and 81% DMC yield together with 90% EC conversion was obtained under mild reaction conditions. Notably, the catalyst could be recycled for four times without loss of catalytic activity. Moreover, a possible mechanism was also discussed.     

An efficient, mild, and selective Ullmann-type N-arylation of indoles catalyzed by copper(I) complex

A wide range of N-arylated indoles are selectively synthesized through intermolecular C(aryl)-N bond formation from the corresponding aryl iodides and indoles through Ullmann-type coupling reactions in the presence of a catalytic amount of easily available N,N,N′,N′-tetramethyl-BINAM-CuI complex under very mild reaction conditions.     

A practical synthesis of 2‐aminobenzothiazoles via copper(I)‐catalyzed tandem reaction of 2‐iodoanilines with isothiocyanates in ionic liquids

A copper(I)‐catalyzed tandem reaction of 2‐iodoanilines with isothiocyanates was achieved in hydrophobic [bmim][PF₆] ionic liquid under mild conditions, generating a variety of 2‐aminobenzothiazoles in good to excellent yields. The tandem reaction that was carried out in [bmim][PF₆] has some obvious advantages such as accelerated reaction rate and increased yield as compared with the reaction run in volatile solvents such as toluene. Furthermore, the CuI/1,10‐phenanthroline catalytic system can be reused up to eight times without loss of activity and efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of glucose-tagged triazolium ionic liquids and their application as solvent and ligand for copper(I) catalyzed amination

Glucose-linked 1,2,3-triazolium ionic liquids have been synthesized as a new class of chiral solvents by copper(I) catalyzed regioselective cycloaddition of a glucose azide with a glucose alkyne followed by quaternization with methyl iodide. The tagging of glucose to triazolium core makes these molecules act as reusable ligand and solvent in copper(I) catalyzed amination of aryl halides with aqueous ammonia. While the free hydroxyl groups of sugar help in stabilizing copper(I) species during the reaction thus acting as a ligand, the triazolium salt which makes it a liquid at room temperature serves as a reusable solvent. These chiral ionic liquids derived from low-cost natural sources can find utility in various transition-metal catalyzed reactions, and can be explored for asymmetric synthesis in future.     

Copper-catalyzed coupling of tertiary aliphatic amines with terminal alkynes to propargylamines via C-H activation

We have developed a convenient and efficient method for coupling of tertiary aliphatic amines with terminal alkynes to propargylamines via C-H activation. The protocol uses CuBr as the catalyst, NBS as the free radical initiator, CH(3)CN as the solvent, and the alkynylation was selectively performed on the methyl of tertiary aliphatic amines at 80 degrees C. This is an economical and practical method for the synthesis of propargylamines.     

Methanolysis of poly(lactic acid) (PLA) catalyzed by ionic liquids

Poly(lactic acid) (PLA) was depolymerized by methanol in the presence of a novel catalyst: ionic liquids. It was found that the purification method of the main products in the methanolysis catalyzed by ionic liquids was simpler than that of traditional compounds, such as sulfuric acid. Qualitative analysis indicated that the main product in the methanolysis process was methyl lactate. The influences of experimental parameters, such as the amount of ionic liquids, methanolysis time, reaction temperature, and dosages of methanol on the conversion of PLA, yield of methyl lactate were investigated. Under the optimum conditions, using ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) as catalyst, results showed that the ionic liquid could be reused up to 6 times without apparent decrease in the conversion of PLA and yield of methyl lactate. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA was a first-order kinetic reaction with activation energy of 38.29 kJ/mol. In addition, a possible catalysis mechanism of the methanolysis of PLA was proposed.