Synergistic effect of dual-frequency ultrasound irradiation in the one-pot synthesis of 3,5-disubstituted isoxazoles

Maria Koufaki; Theano Fotopoulou; Georgios A Heropoulos

doi:10.1016/j.ultsonch.2013.05.012

Synergistic effect of dual-frequency ultrasound irradiation in the one-pot synthesis of 3,5-disubstituted isoxazoles

Ultrason Sonochem. 2014 Jan;21(1):35-9. doi: 10.1016/j.ultsonch.2013.05.012. Epub 2013 May 28.

Authors

Maria Koufaki¹, Theano Fotopoulou, Georgios A Heropoulos

Affiliation

¹ National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry and Biotechnology, 48, Vas. Constantinou Ave., Athens 11635, Greece. Electronic address: mkoufa@eie.gr.

PMID: 23769747
DOI: 10.1016/j.ultsonch.2013.05.012

Abstract

Herein is reported a one-pot three-step process for the regioselective synthesis of 3,5-disubstituted isoxazoles based on copper(I)-catalyzed cycloaddition reaction between in situ generated nitrile oxides (from the corresponding aldehydes) and alkynes, using ultrasound irradiation, avoiding toxic reagents and solvents and isolation/purification of intermediates. The combined use of 40 kHz ultrasonic bath and 20 kHz probe in the presence of copper turnings reduced reaction time to 1h and resulted in only one final purification step with increased yields, clearly indicating that there is a dual-frequency synergistic effect. In addition, under metal free conditions, the 1,3-dipolar cycloaddition was regioselective giving low to modest yields.

Keywords: 1,3-Dipolar cycloaddition; Dual-frequency ultrasound; Isoxazoles.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aldehydes / chemistry
Alkynes / chemistry
Chemistry Techniques, Synthetic
Isoxazoles / chemical synthesis*
Isoxazoles / chemistry*
Ultrasonics*

Substances

Aldehydes
Alkynes
Isoxazoles