Estudos visando a síntese de novos derivados 1,2,4-oxadiazólicos 3,5-dissubstituídos

Abstract

In this work, we synthesized novel 3,5-disubstituted 1,2,4-oxadiazoles. The synthetic strategy was developed via two routes, both using arylamidoximes and chloride 1-adamantanecarbonyl. The first route (Method A) was separated into two steps: in the step 1, the reaction was carried out at room temperature (30 oC), dichloromethane as solvent and inert argon atmosphere. O-Acylamidoxime intermediates were obtained in yields from 16 to 79%. In the step 2, O-acylamidoximes intermediates were subjected to focused microwave irradiation (FMWI) at 110 °C (power 150 W) for 5 min. 1,2,4-Oxadiazole derivatives were obtained in moderate to good yields of 56-84%. Another pathway (Method B), one-pot strategy applying focused microwave irradiation (110 oC, power 150 W, for 5 min) was developed to preparing 1,2,4-oxadiazoles from arylamidoximes and chloride 1-adamantanecarbonyl using DMF as solvent. However, the 1,2,4-oxadiazole derivatives were obtained with low (18%) and good (70%) yields in two cases. Attempts to synthesis of 1,2,4-oxadiazoles from the reaction between ethyl propiolate and arylamidoximes have not been success; however, only O-vinyl derivatives have been prepared.