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A novel three-component reaction between isocyanides, isothiocyanates, and oxiranes has been developed. An array of substituted oxathianes have been obtained in acceptable to good yields. The react...

A naturally biodegradable, reusable, and eco-safe catalyst, i.e., uric acid was developed and exploited for the green, facile and economical one-pot synthesis of pyran annulated heterocyclic system...

A catalytic methodology involving terminal alkynes, elemental sulfur, and three-membered heterocycles has been described. This domino transformation serves as a useful method for the synthesis of oxathiolane and thiazolidine derivatives from the readily available starting materials. In situ generated copper acetylides reacted with elemental sulfur and oxiranes or aziridines in the presence of N-methylpiperidine as sulfur activating agent to form synthetically important heterocycles.

A simple and efficient one-pot process for the synthesis of 1,8-dioxo-octahydroxanthene and 2,2′-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) derivatives via the Knoevenagel–Michael cascade reactions of aromatic aldehydes and dimedone catalyzed by Bronsted acidic ionic liquids (BAILs) in solvent-free and aqueous conditions is described in this study. These heterocycles were prepared in the presence of Bronsted acidic ionic liquids as a suitable, economical, readily synthesized and eco-friendly catalyst. This method offers several advantages such as high yields, simplicity of the workup, low cost, short reaction times, green conditions and use of a reusable catalyst.

Polysubstituted phthalimide derivatives have been isolated in excellent yield from the addition reaction between acetoacetanilide and dialkyl acetylenedicarboxylates by using DABCO as an efficient basic catalyst in EtOH at room temperature. This procedure led to the formation of new phthalimide derivative in the presence of di-tert-butylacetylendicarboxylate as acetylenic ester. The methodology has also been applied successfully for the synthesis of novel piperidine substitutes via the simple reaction between acetoacetanilide and alkyl propiolates. These reactions have some advantages such as not only the process is eco-friendly but also the yields are good and the work-up is simple.

This method reported the use of tartaric acid as a green and highly efficient catalyst for the convenient synthesis of polysubstituted quinolines and xanthenes derivatives in excellent yields under solvent-free conditions. The main advantages of this one-pot procedure are the green and economic availability of the catalyst, simple experimental and work-up procedures.

For the first time, the organic salt Na2EDTA was used as a catalyst for an effective and facile preparation of spiro-4H-pyrans via single-pot three-component condensation of isatin/acenaphthoquinone/ninhydrin, malononitrile, and CH-acids through Knoevenagel–Michael–annulation sequence. This new protocol employing Na2EDTA, which is a green, recyclable, and inexpensive catalyst, offers advantages such as solvent-free and highly efficient reaction conditions, short reaction times (10–15 min), easy work-up and high yields which make it more economic than other environmentally synthetic methods.

A simple and convenient multi-component domino reaction has been described for the synthesis of novel spirofuran-indenoquinoxaline derivatives. Products were obtained by a three-component condensation reaction between ninhydrin, aromatic 1,2-diamines and dialkyl ethynedicarboxylates in the presence of a catalytic amount of triphenylphosphine in $$\hbox {CH}_{2}\hbox {Cl}_{2}$$ at ambient temperature in excellent yields. This one-pot process produces biologically and pharmacologically significant heterocycles with the formation of five new bonds (one C–C, two C=N and two C–O) and two new rings in a single operation.

Three-component processes for the synthesis of 2-amino-4H-chromenes catalyzed by potassium carbonate/cyanuric acid in water as a safe solvent were developed. These reactions were performed at room temperature through one-pot reactions. The benefits of this research are short reaction time, excellent yield, clean reaction media, simple work-up and easy purification.

A convenient, one-pot, multicomponent synthesis of new (4-oxothiazolidine-2-ylidene)benzamide derivatives by unsymmetrical thioureas, various amines and methyl bromoacetate has been developed. These new compounds were characterized by IR, 1HNMR, 13CNMR, mass spectrometry, CHNS elemental analysis, and single-crystal X-ray analysis.

A green, convenient, high yielding and one-pot procedure for the synthesis of novel spiro[benzo[a]pyrano[2,3-c]phenazine] derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamines, ninhydrine, and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) as an expedient, eco-friendly and reusable solid base catalyst under thermal, microwave irradiation and solvent-free conditions. This procedure has also been applied successfully for the synthesis of benzo[a]pyrano[2,3-c]phenazines.

A new three-component reaction was studied kinetically among benzoyl isothiocyanate (1), 1-naphthylamine (2), and methyl bromoacetate (3) in the presence of triethylamine (4) as a catalyst, to yield Z-N-(3-(naphthalene-2-yl)-4-oxothiazolidine-2-ylidene) benzamide (5). The overall reaction is a combination of two reactions; 1) reaction a, between (1) and (2) forming 1-benzoyl-3-(naphthalen-1-yl) thiourea (P1); 2) reaction b, between (P1), (3) and (4) to form the product (5). The rate of reaction a, (kobsa=66.49 M−1 min−1) was more than the reaction b (kobsb=2.9 M−1 min−1), in acetonitrile solvent at 25 °C. A mechanism was proposed involving step1 (kobsa), step2 (k2 ), step3 (k3 ) and step4 (k4 ). Substituent effects with electron-withdrawing groups on para-position of benzoyl isothiocyanate (1) increased the rate constants of kobsa and k2 . The large negative entropy, ΔS‡, values in reactions a, and b are in agreement with step1 (kobsa) and step2 (k 2), an associative mechanism with a negative ΔS‡. The sum of these observations proved that the rate-determining step (RDS) is step2. It seems that the most important steps in the reaction mechanism are step1 (kobsa) and step2 (k2 ), which strongly control the reaction process. The kinetics and mechanism of these reactions were assessed by UV–vis spectrophotometry.

A simple synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via one-pot four-component condensation reaction of phthalimide, hydrazine monohydrate, aromatic aldehyde derivatives and malononitrile in the presence of a catalytic amount of zirconium tetrachloride (ZrCl4) as a mild and efficient Lewis acidic catalyst under thermal and solvent-free conditions with good yields and short reaction times is developed. This present methodology has notable benefits such as high efficiency, inexpensive and non-toxic catalyst, environmentally benign nature, solvent-free conditions and simplicity of operation.

A series of biologically active polysubstituted dihydropyrrol-2-ones are prepared via a one-pot four-component reaction of structurally diverse dialkyl acetylenedicarboxylate, formaldehyde, and amines (aromatic and aliphatic) using a catalytic amount of tartaric acid as a naturally green, mild di-functional Bronsted acid catalyst at ambient temperature. The use of tartaric acid as an inexpensive catalyst makes this procedure eco-friendlier and also one-pot, easily separated from the reaction mixture, good to high yields, short reaction times, simple operational procedures, and highly efficient that are the added advantages of the present methodology.

We have studied the catalytic ability of copper(II) acetate monohydrate as a mild, environmentally benign, natural and economical catalyst for the multi-component efficient synthesis of biologically active spiro-4H-pyran derivatives and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives with excellent yields and short reaction times. The most important advantages of this procedure are its mild, non-toxic and inexpensive catalyst, one-pot synthesis, environmentally benign nature, solvent-free conditions, simple operational procedures, and highly efficient conditions.

A sequential one-pot four-component reaction for the efficient synthesis of novel 16-(aryl)benzo[a]indeno[2′,1′:5,6]pyrano[2,3-c]phenazin-15(16H)-one derivatives has been developed. The synthesis was achieved by reacting 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, aromatic aldehydes, and 1,3-indandione in the presence of oxalic acid as a reusable and homogenous organocatalyst in EtOH/H2O (1:1) under reflux. The present approach of this methodology offers several advantages such as high yields, clean reaction profiles, operational simplicity, simple work-up procedures, and green aspects by avoiding toxic catalysts and solvents.

Phthalic acid as a green, biodegradable economical and environmentally benign nature catalyst for the one-pot three-component Biginelli synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives via β-keto esters, aldehyde derivatives and urea/thiourea under thermal and solvent-free conditions and one-pot four-component domino condensation of substituted dihydro-2-oxypyrrole by reaction of dialkyl acetylenedicarboxylate, formaldehyde and amines (aromatic and aliphatic) under ambient temperature with short reaction times and excellent yields is reported. The most benefits this procedure are such as green, biodegradable, inexpensive and non-toxic catalyst, eco-friendly, high catalytic activity, efficient, easily separation with no column chromatographic separation, simple operational procedures, one-pot, excellent yields, environmentally benign nature.

5-Carboxanilide-dihydropyrimidinone derivatives were prepared by three-component Biginelli reaction of acetoacetanilide, aromatic aldehydes and thiourea in the presence of CeCl3 as an expedient catalyst and used as key intermediates for the highly efficient and eco-friendly synthesis of new and densely functionalized thiazolo[3,2-a]pyrimidin derivatives with use of dimethyl and diethyl acetylenedicarboxylate in ethanol at ambient temperature (conventional magnetic stirring).

A one-pot, two-step procedure has been used to synthesize functionalized benzo[a]pyrano[2,3-c]phenazine derivatives from a four-component condensation reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aldehydes, and malononitrile in the presence of 1,3,7-trimethylpurine-2,6-dione (caffeine) as an expedient and reusable solid base catalyst. This new procedure has the following advantages: operational simplicity, short reaction times, environmentally friendly, easy work-up, and all the products were obtained in excellent yields.

3-(2′-Benzothiazolyl)-2,3-dihydroquinazolin-4(1H)- one, 1-((benzo[d]thiazol-2-ylamino) (aryl)-methyl)naphthalen-2-ol and 4H-pyrimido[2,1-b][1,3]benzothiazoles derivatives were prepared via one-pot three-component reaction of arylaldehydes, 2-aminobenzothiazole and isatoic anhydride or β-naphthol or ethyl/methyl acetoacetate in the presence of agar as a highly efficient homogenous catalyst. The use of a non-toxic and biodegradable catalyst, as well as high yields, short reaction time, simple work-up and green conditions are the most important advantages of this method.

Synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones catalyzed by imidazole or isoquinoline as organocatalyst via the condensation of aromatic aldehydes, dimedone, and β-naphthol was carried out under solvent-free conditions. This method provides several advantages such as short reaction time, environment friendliness, good yields, and simple work-up procedure. .

A efficient one-pot synthesis of C-alkylated phenols and benzofuran derivatives containing phosphanylidene substituents is described. In this reaction triphenylphosphine reacts by nucleophilic addition to dialkyl acetylenedicarboxylates in the presence of phenols to produce stable phosphorus ylides in good yields.

Silica sulfuric acid (SiO2–SO3H) has been used as an effective and reusable solid catalyst for the one-pot, two-step, four-component microwave-assisted synthesis of benzo[a]chromeno[2,3-c]phenazine derivatives by the condensation reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aldehydes, and cyclic 1,3-dicarbonyl compounds. This new procedure has a number of advantages such as: high yields, very short reaction time, operational simplicity, simple work-up procedures and avoidance of hazardous or toxic catalysts, and organic solvents and is devoid of inessential derivatization and generation of hazardous substances. Moreover, the catalyst shows high thermal stability and can be recovered and reused without loss of reactivity.

An efficient and direct protocol is described for the preparation of α-amino phosphonates derivatives by employing a multi-component, one-pot condensation reaction of aldehyde, amine and trialkyl phosphite in the presence of silica-supported perchloric acid (3 mol%) under solvent-free conditions. The thermal solvent-free green procedure offers advantages such as shorter reaction time, simple work-up, high yield, recovery and reusability of catalyst.

A simple, efficient, and environmentally benign method has been developed for the synthesis of α-amino phosphonates. One-pot, three-component reaction of aldehyds, amines, and trialkylphosphite in the presence of silica-supported sodium hydrogen sulfate (NaHSO4-SiO2) as an inexpensive and reusable catalyst under solvent-free conditions at 80 °C affords the corresponding α-amino phosphonates in good yields and short reaction times.

Synthesis of α-amino phosphonates is described under solvent-free conditions at 100°C from reaction between aldehydes and amines in the presence of trialkyl phosphites using Al(H2PO4)3 as an efficient and reusable heterogeneous catalyst. The advantages of this procedure are short reaction time, flexibility and having high to excellent yields.

A simple, efficient, and environmentally benign method has been developed for the synthesis of α-amino phosphonates. One-pot, three-component reaction of aldehyds, amines, and trialkylphosphite in the presence of silica-supported sodium hydrogen sulfate (NaHSO4-SiO2) as an inexpensive and reusable catalyst under solvent-free conditions at 80 °C affords the corresponding α-amino phosphonates in good yields and short reaction times.

Multicomponent reactions involving azines (phenanthridine or isoquinoline) and dimethyl acetylenedicarboxylate were undertaken in the presence of heterocyclic NH compounds (indole, 2-methyl indole, 3-methyl indole, carbazole and 3,6-dibromocarbazole) or 1,3-dicarbonyl compounds such as N,N′-dimethylbarbituric acid, 1,3-diethyl-2-thiobarbituric acid, acetylacetone, 1,3-diphenyl-1,3-propandione and cyclopentan-1,3-dione to generate enaminoesters in good yields.

A new one-pot, simple and effective procedure is presented for the preparation of O-containing phosphorus ylides by the Michael addition reaction of N-methylpyrrole-2-carbaldehydoxime, pyridin-2-carbaldehydoxime or acetophenonoxime with acetylenic esters.

By cycloaddition reaction of sodium azide with chalcone in the presence of CuO as a catalyst in DMF a 1,2,3-triazole are prepared in reaction with pentafluoropyridine to give 2-(tetrafluoropyridin-4-yl)-1,2,3-triazole derivatives in good yields and high regioselectivity. The regioselectivity of the compounds are confirmed by 19F-NMR and other spectroscopy. Graphical Abstract