**3. Concluding remarks**

Reactive fluorescent coumarins have been increasingly attracting special interest as fluorescent labels, with a wide range of applications in bioimaging and biolabelling, due to their extremely attractive and stable scaffold. Coumarins will allow the development of new low-cost fluorescent dyes due to its easy synthesis with high yields, large Stokes shift, pH independence of absorbance and emission, and excellent photostability, which represents a great value for the biological fluorescence imaging techniques.
