ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

3,5-Disubstituted-1H-pyrazoles: sequential syntheses from N-acylbenzotriazoles, alkynes, and hydrazine in ionic liquid

Khalid Widyan

Department of Chemistry and Chemical Technology, Tafila Technical University, Tafila, Jordan

E-mail: k.widyan@ttu.edu.jo

Received: 17 September 2024  Accepted: 26 December 2024

Abstract:

A new procedure that is free of copper and palladium has been developed for the sequential synthesis of 3,5-disubstituted-1H-pyrazoles using various N-acylbenzotriazoles, terminal alkynes, and hydrazine. In this process, N-acylbenzotriazoles react with terminal alkynes in 1-butyl-3-methyl-imidazolium tetrafluoroborate, catalyzed by zinc chloride, to produce α,β-unsaturated alkynones. These intermediates are then converted into pyrazoles through an in-situ reaction with hydrazine. Additionally, the ionic liquid can be recovered and reused without significant loss of efficiency.

Keywords: Pyrazoles; N-acylbenzotriazoles; Terminal alkynes; Ionic liquid; Sequential syntheses

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-024-03880-x

Chemical Papers 79 (3) 1649–1655 (2025)