Facile synthesis of indolizines using layered double hydroxides@poly( p ‐phenylenediamine) as a catalyst with a green tool (neat technology)

Ionic Liquid-Assisted Fabrication of Bioactive Heterogeneous Magnetic Nanocatalyst with Antioxidant and Antibacterial Activities for the Synthesis of Polyhydroquinoline Derivatives

Antibacterial materials have obtained much attention in recent years due to the presence of hazardous agents causing oxidative stress and observation of pathogens. However, materials with antioxidant and antibacterial activities can cause toxicity due to their low biocompatibility and safety profile, urging scientists to follow new ways in the synthesis of such materials. Ionic liquids have been employed as a green and environmentally solvent for the fabrication of electrically conductive polymers. In the present study, an antibacterial poly(p-phenylenediamine)@Fe3O4 (PpPDA@Fe3O4) nanocomposite was fabricated using [HPy][HSO4] ionic liquid. The chemical preparation of PpPDA@Fe3O4 nanocomposite was initiated through the oxidative polymerization of p-phenylenediamine by ammonium persulfate in the presence of [HPy][HSO4]. The PpPDA@Fe3O4 nanocomposite exhibited antibacterial properties against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria. The PpPDA@Fe3O4 nanocomposite was employed as a heterogeneous nanocatalysis for one-pot synthesis of polyhydroquinoline derivatives using aromatic aldehyde, dimedone, benzyl acetoacetate, and ammonium acetate. Polyhydroquinoline derivatives were synthesized in significant yields (90-97%) without a difficult work-up procedure in short reaction times. Additionally, PpPDA@Fe3O4 nanocatalyst was recycled for at least five consecutive catalytic runs with a minor decrease in the catalytic activity. In this case, 11 derivatives of polyhydroquinoline showed in vitro antioxidant activity between 70-98%.

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.

One-pot synthesis of benzopyrano[2,3-d]pyrimidine derivatives catalyzed by LDHs@Propyl-ANDSA

A general, effective, and operationally simple approach to highly substituted benzopyrano[2,3-d]pyrimidine through the annulation of salicylaldehydes, malononitrile, and secondary amines is explained. The reaction is promoted by the Brønsted–Lowry acid, furnishing a variety of benzopyrano[2,3-d]pyrimidine derivatives in synthetically useful yields.