An Efficient Synthesis and Fluorescent Properties of Pyrazole[3,4-b]thieno[2,3-e]pyridine Derivatives

A simple and efficient method for the synthesis of pyrazole[3,4‐b]thieno[2,3‐e]pyridine derivatives via the sequence of three‐component, catalyst‐free, and solvent‐free condensation and oxidation was described. The products feature a donor‐π‐conjugated acceptor fluorescent activity system, and the fluorescence emission wavelength was measured in methanol. Some products were fluorescent in solution emitting at blue light (λem = 430–505 nm).