Coumarin and its derivatives are widely used as scaffolds in the synthesis of new heterocyclic systems. This review focuses on current developments in the synthesis of heterocyclic coumarin compounds. Numerous approaches especially involving nanoparticle catalysts have been developed to get new bioactive coumarin derivatives endowed with pharmacological and biological activities. The present work describes the reactivity and the new strategies using various catalysts for the synthesis of coumarin and its derivatives reported in the literature and their biological properties.

The synthesis of N-methyl-5-nitroindazolylacrylonitriles 2 a-l by a Knoevenagel condensation reaction with a series of aldehydes in the presence of piperidine allowed the preparation of the desired products the yields are good to excellent. N-Methyl-5-nitroindazolylacrylonitriles (2 a-l) were verified by 1 H, 13 C NMR and mass spectrometry. In this current work, the reactivity indices defined within the Conceptual DFT of the targeted molecules through DFT/B3LYP/6-311G(d,p) calculations were studied. The 1 H NMR, UV-vis and IR spectroscopy chemical shifts of all synthesized 5-nitroindazoles 2 a-l were calculated and the results were compared to the results of the experimental data. In this series of compounds, the 2 e has the lowest hyperpolarizability, which results being the most stable and having the least response to nonlinear optics (NLO). In contrast, the compound 2 l has the highest hyperpolarizability, which fallouts being the least stable and having a high response to NLO. Every chemical has a significant threedimensional p-electronic delocalization, which is crucial for understanding NLO responses.