One-Step Protection-Free Synthesis of 3-Aryl-5-hydroxyalkyl-1,2,4-oxadiazoles as Building Blocks

Abstract

A simple and straightforward synthesis of 3-aryl-5-hydroxyalkyl-1,2,4-oxadiazoles is described. The reaction among arylamidoximes, ethyl glycolate or ethyl lactate, and potassium carbonate in refluxing toluene afforded the desired 1,2,4-oxadiazoles in moderate to good yields. The synthesis has been accomplished in a single step, avoiding protection–deprotection protocols.

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GRAPHICAL ABSTRACT

Keywords:

• Cyclodehydration
• 1,2,4-oxadiazoles
• thermal reaction

ACKNOWLEDGMENTS

Our thanks go to the Brazilian National Research Council (CNPq) and Pernambuco State's Scientific and Research Foundation (FACEPE, PRONEX-0788-1.06/08 CNPq) for providing financial assistance. One of us (R. A. W. N. F.) is grateful to CNPq for a technician's fellowship.

Notes

^a Experiment performed at 25 mmol scale.

^b Yields in parenthesis indicates the use of 7:3 toluene:DMF (V/V) system during the reaction.