Synthesis of Pyrazoles via Electrophilic Cyclization of Alkynes Containing Thiophene

Background: Pyrazole is a simple aromatic ring an organic compound of the heterocyclic series that characterized five-membered ring structure which comprises located adjacent two nitrogen atoms and three carbon atoms. In recent years interest in the pyrazole chemistry excessively has increased due to many a wide range of properties. Because they have a wide range of specific properties such as biological activities, pharmaceutical i.e., Pyrazoles were also applied successfully in many fields; medicine, agricultural, industry, pharmaceutical chemistry so that pyrazole chemistry was quite an interesting area of research for the synthesis of their derivatives and investigates new methods. Methods: Research and online content related to synthesis pyrazole and electrophilic cyclization of molecules are reviewed. Excerpts are used to illustrate key themes about chemistry of organic substances bearing pyrazole group. All the solvents and chemical materials were purchased. All the reagents were used directly without purification. Results: The new substitute α,β-alkynic hydrazones was prepared by heating directly from thiophene-2-acetyl chloride and terminal alkyne via a palladium-catalyzed coupling reaction then a series of the new substituted pyrazole derivatives were converted via electrophilic cyclization by catalyst and characterizations of each compound were indicated by the help of spectral data. Conclusion: The new different substitute pyrazoles were synthesized via copper mediated electrophilic cyclization. Firstly, the various hydrazones derivatives were carried out by the condensation reactions of the propargyl ketone that prepared from phenyl acetylene and acyl chloride with hydrazines. The various pyrazoles contain that thiophene were obtained by electrophilic cyclization copper(I) iodide and the various hydrazones. In addition, synthesized of substitute pyrazoles may be apply the other fields because of their diverse and potent biological properties. For this reason, the syntheses of different pyrazole compounds are becoming more importance. Keywords: Alkyne, electrophilic cyclization, hydrazine, hydrazone, pyrazole.