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Relevant academic research and scientific papers

A rapid and an efficient route to the one-pot, multicomponent synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione ring systems

CAN is found to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via one-pot coupling reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in PEG as solvent. The major attributes of this synthetic protocol are the use of nontoxic, inexpensive, and readily available catalyst, mild conditions, easy work up, improved yields, and the PEG 400 as solvent that is environmentally benign as well as recyclable.

Experimental and DFT mechanistic insights into one-pot synthesis of 1: H -pyrazolo[1,2- b] phthalazine-5,10-diones under catalysis of DBU-based ionic liquids

Benzylation of DBU followed by anion exchange of the resulting salt with trifluoroacetate gave nearly quantitatively the ionic liquid [Bn-DBU][TFA]. It is shown here to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones via the three-component reaction of phthalhydrazide, aromatic aldehydes, and active α-methylene nitriles. DFT calculations at the B3LYP/SVP level and the experimental results are in agreement with a three-step mechanism for this reaction. Based on the DFT calculations, the catalytic effect largely arises from the intrinsic ionic properties of the ionic liquid rather than its action as a simple base. These calculations also predict the existence of two close-in-energy activated complexes whose rate determining roles and energies depend on their interaction with the anionic component of the ionic liquid, as [Bn-DBU][TFA] has shown a higher catalytic activity than [Bn-DBU][OAc]. This mechanistic approach opens up new and promising insights into the rational design of ionic liquid catalysts for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones. The synthetic method presented here has several prominent advantages.

Mild preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives with magnetic Fe3O4 nanoparticles coated by (3-aminopropyl)-triethoxysilane as catalyst under ambient and solvent-free conditions

An efficient, one-pot quantitative procedure for preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives from four-component condensation reaction of hydrazine monohydrate, phthalic anhydride, malononitrile or ethyl cyanoacetate, and aromatic aldehydes in the presence of magnetic Fe3O4 nanoparticles coated by (3-aminopropyl)-triethoxysilane as catalyst under mild, ambient, and solvent-free conditions is described. Simple procedure, high yield, short reaction time, and environmentally benign method are advantages of this protocol. The magnetic Fe3O4 nanoparticles coated by (3-aminopropyl)-triethoxysilane can be recovered and reused several times without loss of activity.

One-pot four-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10- dione derivatives

The synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives by NiCl2-catalyzed novel one-pot four-component condensation reaction of phthalimide, hydrazine, malononitrile (or ethyl cyanoacetate), and aromatic aldehydes was reported. This work provides a simple, efficient, and eco-friendly method for the construction of pyrazolo[1,2-b]phalazine-5,10-dione derivatives.

Mild basic ionic liquids catalyzed new four-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

A new four-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives using three weak basic ionic liquids such as 1,8-diazabicyclo[5.4.0] -undec-7-en-8-ium acetate, pyrrolidinium formate, and pyrrolidinium acetate as efficient catalysts for condensation reaction of hydrazine monohydrate, phthalic anhydride, malononitrile or ethyl cyanoacetate, and aromatic aldehydes under ambient and solvent-free conditions in excellent yields is described.

A highly efficient green synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10- dione derivatives and their photophysical studies

A task-specific ionic liquid, [Bmim]OH, has been used for an efficient synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by one-pot cyclocondensation reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate under microwave irradiation. The advantages of this method include the use of green catalyst, no organic solvent, easy work-up and excellent yields. The photophysical properties for some 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives have been investigated for the first time.

Ultrasound-assisted one-pot, three-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

Triethylamine was found to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by one-pot reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in ethanol under ultrasonic irradiation. The advantages of this method are the use of an inexpensive and readily available catalyst, easy workup, improved yields, and the use of ethanol as a solvent that is considered to be relatively environmentally benign.