Síntese de 5-alquil (aril)-3-triclorometil-1,2,4-oxadiazóis

Abstract

Thirteen 5-alkyl(aryl)-3-trichloromethyl-1,2,4-oxadiazoles were synthetized from one-pot reaction of trichloroacetoamidoxime with acyl chlorides (R-C(=O)Cl when R= Me, Et, Pr, CH2Cl, CHCl2, CCl3, Ph, 4-nitrophenyl, 2-fluorophenyl, 4-methylphenyl, 2-iodophenyl, 2-methoxyphenyl, 3-bromophenyl). Eight of them were never previously reported in the literature. The best reaction condition was using toluene as the solvent at 110°C with good yields (61-90%). Solvents such as ethyl ether, dichloromethane, chloroform, tetrahydrofuran and acetic acid did not show good yields. The reaction without any solvent did not provide the formation of the desire oxadiazole. All compounds were identified and fully characterized by NMR 1H and 13C and by mass spectrometry. This work also describes the synthesis of intermediate trichloroacetoamidoxime in a mild conditions reactions using water at room temperature for 20 hours in excellent yields (99%). The literature condition requires refluxing of ethanol for 24 hours and the yield is low (64%). This intermediate was identified by X-ray diffraction and by melting point data.