Regioselective synthesis of some new pyrazole and isoxazole derivatives incorporating benzothiazole moiety: Experimental and theoretical studies

Abstract

Nitrile imine derivative 3 added regioselectively to α-(benzothiazol-2-yl)cinnamonitrile derivatives 1a–c to afford 5-(benzothiazol-2-yl)-5-cyano-4,5-dihydro-1H-pyrazole derivatives 4a–c. Compound 4a underwent thermal elimination of hydrogen cyanide in sodium ethoxide solution to give the pyrazole derivative 6. The isoxazole derivative 10 was synthesized by reacting nitrile oxide 8 with cinnamonitrile derivative 1d. The structures of the synthesized compounds were characterized by FT-IR, NMR, and MS spectroscopic techniques. The reaction mechanism was studied via density functional theory (DFT) quantum chemical calculations at the B3LYP/6-31G (d) level of theory.

Graphical Abstract

Keywords:

• Benzothiazole
• computational calculations
• 1,3-dipolar cycloaddition
• isoxazole
• pyrazole

Acknowledgments

The authors extend their sincere appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through Small Groups (Grant number RGP1/57/44).

Declaration of interest

No potential conflict of interest was reported by the authors.

Data availability statement

The data that supports the findings of this study are available in the supplementary material of this article.

Additional information

Funding

This work was supported by the Deanship of Scientific Research at King Khalid University (Grant number RGP1/57/44).