A simple and efficient one-pot procedure has been developed for the construction of pyrrolo[1,2-a]pyrimidines via the three-component domino reaction of 5-aminopyrazoles, acetylenedicarboxylates and malononitrile under catalyst-free, microwave irradiation conditions. The key step in this transformation is the NN bond cleavage reaction of the 5-aminopyrazole substrate, which has been reported in this context for the first time in this study. The advantages of this protocol include readily available starting materials, short reaction times and good regioselectivity.

A series of 5-aryl-1H-pyrazole derivatives were synthesized via the reaction of 3-(dimethylamino)-1-arylprop-2-en-1-one with hydrazine in aqueous media without using any catalyst. This method has the advantages of easier work-up, mild reaction condition, high yields, and an environmentally benign procedure.

An efficient, convenient Cu-catalyzed formation of chromeno[4,3-c]pyrazol-4(1H)-ones is reported. In this atom economic process, readily available 3-acylcoumarin hydrazone is oxidative cyclized by direct C–N bond formation. Air has been successfully used as an oxidant, which has important economic and environmental advantages. A broad scope of 3-acylcoumarin hydrazones can be utilized in this process.

A facile and efficient one-pot procedure for the preparation of indeno[1,2-b]indole derivatives via three-component domino reaction of ninhydrin, enaminones, and malononitrile catalyzed by L-proline is described. In this reaction, two rings and four bonds were formed by one-pot.

A series of chromeno[4,3-d]isoxazolo[5,4-b]pyridin-6-one derivatives were easily and efficiently synthesized by the reaction of 3-acyl-2H-chromen-2-ones with isoxazol-5-amine in acetic acid. Some synthesized compounds were evaluated for their antiproliferative properties in vitro against cancer cells, and these compounds were found to have some activities.

An environmentally benign and efficient method has been developed for the synthesis of functionalized tetrahydroindole derivatives in aqueous media under catalyst-free conditions, by simply combining a phenylglyoxal monohydrate, an enaminone, and a barbituric acid. The advantages of this method are that it is catalyst free, has an easy workup, provides good yields, and uses water as solvent, which make this procedure facile and practical.

A improved and efficient procedure for the synthesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives via the reaction of isatin and enaminone catalyzed by ceric ammonium nitrate under ultrasonic condition has been developed. Compared with the conventional methods, the remarkable advantages of this method are mild reaction conditions, operational simplicity, higher yield, and shorter reaction times.

A simple and efficient synthesis of pyrrolo[2,3,4-kl]acridine-1-one derivatives via the cascade reaction of isatins with enaminones catalyzed by silica sulfuric acid (SSA) has been established. In this reactions, SSA shows a highly catalytic nature: easy to handle procedure, short reaction time, recycle exploitation, insensitivity to air and moisture, and excellent isolated yields. The catalyst could be recycled at least five times.

A series of 5-arylisoxazole and 5-aryl-1H-pyrazole derivatives was synthesized by the reaction of 3-(dimethylamino)-1-arylprop-2-en-1-one with hydroxylamine hydrochloride or hydrazine hydrate under ultrasound irradiation without using any catalyst. This method has the advantages of easier work-up, mild reaction condition, high yields, shorter reaction time, and environmentally benign procedure.

A series of chromeno[4,3-d]pyrazolo[3,4-b]pyridin-6(3H)-one derivatives was easily and efficiently synthesized by the reaction of 2H-chromen-2-ones with pyrazol-5-amines catalyzed by CuCl₂⋅2H₂O in ethanol. This protocol has the advantages of mild reaction conditions, easy work-up, and high yields. These compounds were showed to have high fluorescence quantum yields, which mentioned their value as luminescence or fluorescence probe.

A series of new dispiropyrrolidine derivatives were synthesized via the three-component 1,3-dipolar cycloaddition reaction of azomethine ylides generated in situ by the decarboxylative condensation of acenaphthenequinone and sarcosine or l-thioproline with 5-benzylidene-1,3-dimethylpyrimidine-2,4,6-trione. The structures of the products were identified by IR, ¹H-NMR, and HRMS spectra.

An efficient one-pot synthesis of spiro[indoline-3,1′-pyrazolo[1,2-b]phthalazine] derivatives via three-component reaction of phthalhydrazide, isatin, and malononitrile (cyanoacetic ester) is described. This new protocol has the advantages of high efficiency, mild reaction conditions, one-pot procedure, and convenient operation.

A facile and eco-friendly approach for the synthesis of 6-amino-3-phenyl-4-aryl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives via four-component reaction of hydrazine, ethyl 3-oxo-3-phenylpropanoate, aldehydes, and malononitrile is described. The reaction is performed in water, without using any catalyst, and under ultrasound irradiation. The developed sonochemical-assisted multi-component reaction provides an improved and accelerated conversion when compared with conventional procedure.

L-Proline is found to be an efficient catalyst for the synthesis of tetrahydrofuro[3,4-b]quinoline-1,8(3H,4H)-dione derivatives. This protocol is novel and has the advantages of mild condition, high yield, and easy operation. J. Heterocyclic Chem., (2012).

A series of 4-aryl-3,7,7-trimethyl-1-phenyl-7,8-dihydro-1H-pyrazolo[3,4-b]quinolin- 5(6H)-ones were synthesized by the three-component reaction of aromatic aldehydes, 3-methyl-1-phenyl-1H-pyrazol-5-amine, and 5,5-dimethyl-1,3-cyclohexandione in the presence of sodium 1-dodecanesulfonate in aqueous medium. Compared to the previous methods, this new protocol has the advantages of convenient operation, higher yields, lower cost, and environmentally benign procedure. J. Heterocyclic Chem., (2012).

A new type anion receptors containing indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine have been synthesized via three-component reaction of aldehyde, 6-aminopyrimidine-2,4-dione, and 1,3-indanedione in aqueous media. The binding properties of the receptors with anions such as F⁻, Cl⁻, Br⁻, AcO⁻, HSO₄⁻, and H₂PO₄⁻ have been investigated by UV–vis spectroscopy methods. The results have shown that receptors have good selectivity to F⁻ and AcO⁻, and a 1:1 stoichiometry complex has been formed between compounds and anions.

Synthesis of 3,3′,4,4′-tetrahydro-4,4′-bibenzo[e][1,3]oxazine-2,2′-diones via reaction of salicylidendphenylhydrazone and triphosgene with the aid of low-valent titanium reagent is described. This method has the advantages of accessible starting materials, good yields and short reaction time.

A series of 4-aryl-3,7,7-trimethyl-1-phenyl-7,8-dihydro-1H-pyrazolo[3,4-b]quinolin-5(6H)-ones were synthesized via the three-component reaction of aromatic aldehydes, 5,5-dimethyl-1,3-cyclohexandione and 5-amino-3-methyl-1-phenylpyrazole in ionic liquid without using any catalyst. This protocol has the advantages of easier work-up, milder reaction conditions, short reaction time, and environmentally benign procedure. J. Heterocyclic Chem., (2011).

A short and facile synthesis of 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazolin-5(1H)-ones and 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-diones in good yields via the novel reductive cyclization of 2-nitrobenzamides with haloketones or 4-oxopentanoic acid promoted by low-valent titanium reagent is described. J. Heterocyclic Chem., (2011).

A series of dihydrothiphenes derivatives were synthesized via the four-component reaction of aldehyde, malononitrile, 1,3-thiazolidinedione, and piperidine at room temperature under ultrasound irradiation. Compared with the conventional methods, the remarkable advantages of this method are operational simplicity, higher yield, and shorter reaction time. J. Heterocyclic Chem., (2011).

A series of dispiropyrrolidine derivatives were synthesized via the three-component 1,3-dipolar cycloaddition reaction of isatin, sarcosine and 5-arylidene-1,3-thiazolidine-2,4-dione or 5-arylidene-4-thioxo-1,3-thiazolidine-2-one in ethanol under ultrasound irradiation. This protocol has the advantages of mild reaction conditions, higher yields, and shorter reaction time. J. Heterocyclic Chem., (2011).

A series of hexahydroquinoline derivatives were synthesized by the three-component reaction of 5,5-dimethyl-3-aminocyclohex-2-enone, aromatic aldehyde, and acyl acetonitrile in ionic liquid without using any catalyst. This protocol has the advantages of easier work-up, milder reaction conditions, high yields, and environmentally benign procedure. J. Heterocyclic Chem., (2011).

A series of 3-methyl-1,4-disubstituted-4,5-dihydro-1H-pyrazolo[3,4-b]pyridine-6(7H)-ones was synthesized via the three-component reaction of aldehyde, 3-methyl-1-phenyl-1H-pyrazol-5-amine, and Meldrum's acid catalyzed by L-proline. This protocol has the advantages of easier work-up, milder reaction conditions, and high yields. J. Heterocyclic Chem., (2011).

A series of 5-benzylidenepyrimidine-2,4,6(1H,3H,5H)-trione and 5,5′-(arylmethylene) bis[6-aminopyrimidine- 2,4(1H,3H)-dione] derivatives were synthesized via the three-component reactions of aromatic aldehyde, 6-aminopyrimidine-2,4-dione and Medrum's acid in aqueous media in the presence of triethylbenzylammonium chloride. The structures of the products were affected by substituents of aromatic aldehydes.

The Michael addition reaction of α,β-unsaturated ketones with malononitrile catalyzed by KF-montmorillonite was investigated. It was interesting to note that at different reaction temperatures the addition and cycloaddition reaction products were obtained. This method has the advantages of good yields, mild reaction conditions, easy work-up and inexpensive reagents over the existing procedures.

Various biologically important quinoxaline derivatives were efficiently synthesized in excellent yields by the reaction of 1,2-diketones and 2-nitroaniline, benzofuroxan or 1,2-dinitrobenzene promoted by SnCl₂2H₂O. The role of stannous chloride is acting as both reductive agent and catalyst in this synthesis. This new method has the advantages of accessible starting materials, convenient manipulation, short reaction time and high yields.