Ultrasound-promoted synthesis of 3-trichloromethyl-5-alkyl(aryl)-1,2,4-oxadiazoles

Abstract

The alternative synthesis of 12 1,2,4-oxadiazoles using ultrasound irradiation from trichloroacetoamidoxime and acyl chlorides is reported. Seven of them are novel compounds. The 3-trichloromethyl-5alkyl(aryl)-1,2,4-oxadiazoles have been synthesised in better yields and shorter reaction times compared to the conventional method. This protocol can be applicable for preparation of 1,2,4-oxadiazoles containing aryl or alkyl groups attached at their C-5 side-chain.

1,2,4- and 1,3,4-Oxadiazoles as Scaffolds in the Development of Antiparasitic Agents

“…43 It is also possible to find protocols employing ultrasound irradiation to synthesize 1,2,4-oxadiazoles (29), as reported by Bretanha et al 44 Short reaction times (15 min) and high yields (84-98%) were reported for the reaction between trichloroacetoamidoxime (27) and the properly substituted benzoyl chlorides (28) in ethyl acetate as solvent (Scheme 4). 44 In a different approach, Yoshimura et al 45 reacted nitrile oxides (34) and nitriles (31) to obtain 1,2,4-oxadiazoles (32). Hydroxy(aryl)iodonium (IBA-OTf, 33) was employed allowing the formation in situ of nitrile oxides (34) from the respective nitriles (31).…”

A mild convenient ultrasound assisted synthesis of 2-aryl benzoxazoles catalyzed by KCN/MWCNT as an efficient heterogeneous nanocatalyst

“…Chemical reactions can be catalyzed under ultrasound irradiation through acoustic cavitation: formation, growth and collapse of bubbles [48]. Cavitation process transforms the ultrasonic energy into hot spots which can be considered as microreactors [49]. In other words, cavitation provides intense local temperature, high pressures and cooling rates [50].…”

1,2,4-oxadiazole: A Brief Review from the Literature About the Synthesis and Pharmacological Applications

“…Mechanistically the process passes by the formation of an intermediate 4,5-dihydro-1,2,4-oxadiazole (oxadiazoline) that undergoes the oxidation in the reaction conditions. Scheme 12 -Reaction scheme for the synthesis of 1,2,4-oxadiazole proposed by ADIB et al (2006) Recently it was published in the literature a synthetic procedure using irradiation by ultrasound (USI) in the synthesis of oxadiazole (BRETANHA et al, 2011). In this work the authors report the synthesis of 12 oxadiazole derivatives containing the trichloromethyl group in the position 3 and different alkyl and aryl groups in the position 5 obtained by the reaction of trichloroacetamidoxime with the appropriated acyl chloride (Scheme 13).…”