{[1,4-DHPyrazine][C(CN)(3)](2)} as a New Nano Molten Salt Catalyst for the Synthesis of Novel Piperazine Based bis(4-hydroxy-2H-chromen-2-one) Derivatives

In this article a convenient method for the synthesis of novel piperazine based bis(4-hydroxy-2H-chromen-2-one) derivatives using pyrazine-1,4-diium tricyanomethanide {[1,4-DHPyrazine][C(CN)(3)](2)} as a new nanostructured molten salt (NMS) catalyst has been described. These compounds were synthesized via Mannich type reaction between several aromatic aldehyde, piperazine and 4-hydroxycoumarin under solvent-free condition at room temperature. The NMS catalyst was fully characterized via Fourier transform infrared (FT-IR), nuclear magnetic resonance (H-1 NMR and C-13 NMR), mass spectrometry, thermal gravimetric, derivative thermal gravimetric, differential thermal analysis, X-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy analysis. The new compounds synthesized by using this NMS catalyst were also characterized by FT-IR, H-1 NMR and C-13 NMR, high-resolution mass spectrometry techniques. The new NMS catalyst simply recovers and can be reused several times without significant loss of catalytic activity. The major advantages of the described method in comparison to the classical reactions are low catalyst loading, short reaction time, high yields, simple isolation of product and reusability of the NMS catalyst.

Pyrazine-1,4-diium tricyanomethanide as a nano molten salt catalyst was designed, synthesized and used for the synthesis of novel biological piperazine based bis(4-hydroxy-2H-chromen-2- one) derivatives as bioactive and drug candidates.

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