An Efficient and Facile Synthesis of 1H-Pyrazolo[1,2-b]phthalazine-5,10-dione Derivatives of Biological Interest

Superparamagnetic Polyaniline-co-m-phenylenediamine@Fe3O4 Nanocomposite as an Efficient Heterogeneous Catalyst for the Synthesis of 1H-pyrazolo [1,2- a]pyridazine-5,8-diones & 1H-pyrazolo[1,2-b]phthalazine-5, 10-diones" Instead of 1H-pyrazolo[1,2-b] Phthalazinedione Derivatives

BACKGROUND

The use of polymer-based catalysts has increased because of their high potential application as an effective catalyst in organic reactions. They have benefits such as high efficiency and reactivity, simple separation, and safety compared to other heterogeneous catalysts.

AIM AND OBJECTIVE

The objective of the current research is to prepare solid polymer-based catalysts, poly(aniline-co- m-phenylenediamine) (PAmPDA), and its superparamagnetic nanocomposite. Then, the catalytic activity of the resulting superparamagnetic nanocomposite was investigated in the synthesis of 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives. A series of some 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives was tested for its antibacterial properties against the Staphylococcus aureus and E.coli bacteria.

MATERIALS AND METHODS

PAmPDA copolymer was synthesized in a 1:2 molar ratio of Ani to mPDA via radical oxidative polymerization at room temperature. Superparamagnetic PAmPDA@Fe3O4 nanocomposite was synthesized from a mixture of Fe(II), Fe(III) solution, and PAmPDA copolymer via the in-situ co-precipitation technique. 1H-pyrazolo[1,2-b]phetalazine-5,10-diones were synthesized via one-pot three-component condensation reaction of Phthalhydrazide, aromatic aldehyde derivatives, and malononitrile in the presence of PAmPDA under solvent-free conditions at 80 °C. The synthesis of 1Hpyrazolo[1,2-a]pyridazine-5,8-dione derivatives was carried out via a one-pot three-component condensation reaction of maleic hydrazide, aromatic aldehyde derivatives, and malononitrile in the presence of PAmPDA under reflux conditions at EtOH/H2O 1:1. The antibacterial activity of some derivatives was tested against Gram-positive and Gram-negative bacteria.

RESULTS

First, superparamagnetic PAmPDA@Fe3O4 nanocomposite was synthesized and characterized successfully, and then the resulting nanocatalyst was used for the synthesis of pyrazolo[1,2-b]phthalazine and pyrazolo[1,2-a]pyridazine. We obtained the maximum yield of the desired 1H-pyrazolo[1,2- b]phthalazine-5,10 dione derivatives with 0.05 g of catalyst at 80°C, under solvent free conditions, whereby the reaction was complete within 30 min. A wide range of 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives were synthesized in good to excellent yield. On the other hand, pyrazolo[1,2- a]pyridazine derivative was synthesized successfully in high yield using PAmPDA as a nanocatalyst. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good activity against Staphylococcus aureus and E.coli.

CONCLUSION

In this research, PAmPDA was used for mild preparation of 1H-pyrazolo [1,2-a]pyridazine5,8-diones & 1H-pyrazolo[1,2-b]phetalazine-5,10-diones derivatives with excellent yields and short reaction times. The attractive features of this protocol are simple procedure, cleaner reaction, and the use of recyclable nanocatalyst. Satisfactory yields of products and easy workup make this a useful protocol for the green synthesis of this class of compounds. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good activity against Staphylococcus aureus and E.coli.

In vitro and in silico lipoxygenase inhibition studies and antimicrobial activity of pyrazolyl-phthalazine-diones

The series of pyrazolyl-phthalazine-dione derivatives (PPDs) was subjected to evaluation of their in vitro lipoxygenase (LOX) inhibition and antimicrobial activities. Results obtained for LOX inhibition activities of PPDs showed that all compounds exhibit good to excellent activity, whereby compounds with eudesmic, syringic, vanillic or toluic moiety are the most active. Molecular modelling study was performed to investigate the possible mechanism of action and binding mode of compounds within the LOX active site. Docking results revealed that activity of the examined compounds depends on the functional group ability to create hydrogen bond accepting (HBA) and hydrophobic features (Hy) in the LOX-Ib active site. In addition, all substances were tested for their antibacterial and antifungal activities. The investigated compounds showed better antifungal than antibacterial activity. The highest antifungal activity was on Aspergillus fumigatus ATTC 204305 and Trichoderma viridae ATCC 13233.

DMAP as a new efficient catalyst for the one-pot synthesis of condensed phthalazines

A new, convenient, and efficient method for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones is developed starting from phthalhydrazide, aromatic aldehydes, and malononitrile using 4-N,N-dimethylaminopyridin as catalyst. This modified route provides much higher yields and a simple work-up procedure of products. Also this methodology is of interest due to the use of ethanol as a solvent without use of any toxic metals as catalyst, thus minimizing the cost, the operational hazards, and environmental pollution.

Four-Component Synthesis of 3-Amino-1-Aryl-5,10-Dioxo-1H-Pyrazolo[1,2-b] Phthalazine-2-Carbonitrile Derivatives Promoted by Potassium Carbonate

The one-pot, four-component reaction of phthalic anhydride, hydrazine hydrate, aromatic aldehydes and malononitrile afford 3-amino-1-aryl-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile derivatives in the presence of potassium carbonate in ethanol under reflux conditions. These conditions offer simplified operation, easy purification, excellent yields and environmentally benign reaction conditions. Also, this method avoids the use of expensive catalysts, toxic solvents and chromatographic separation.

New N-arylamino biquinoline derivatives: synthesis, antimicrobial, antituberculosis, and antimalarial evaluation

A new series of N-arylamino biquinoline derivatives 5a-x were synthesized by reaction of 2-chloro-3-formyl quinolines 2a-d with malononitrile and various enhydrazinoketones 4a-f in absolute ethanol. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against a representative panel of pathogenic strains and antituberculosis activity against Mycobacterium tuberculosis H37Rv. Compounds 5h and 5s exhibited excellent antibacterial activity and some of the compounds demonstrated moderate antituberculosis activities compared with the first line drugs. The compounds were evaluated in vitro for their activity against the growth of Plasmodium falciparum, the malaria causing parasite. Some of them showed antimalarial activity with IC(50) values as low as 0.005-0.009 μg/mL.