Estudo de uma nova série de o-glicosídeo 2,3-insaturados : síntese, caracterização e atividade antitumoral

Abstract

This work includes the synthesis an characterization of some new derivatives of bis or tris-1,2,4-oxadiazoles 49a-e and 53a-e and 2,3-unsaturated O-glycosides (54a-e) containing as aglycone 1,2,4-oxaziazole. Arylamidoximes are prepared by treating the corresponding arylnitriles with hydroxylamine hydrochloride in the presence of base afforded the compounds 42a-g under ultrasonic irradiation. The products 42a-g were obtained in a short reaction time (45-90 min) with moderate and high yields (40% - 92%). The 1,2,4-oxadiazoles 50a-e, 53a-e e 49a-e were synthesized by treatment of arylamidoximes 42a-g with diethyl 1,3-acetonedicarboxylate, trimethyl citrate and diethyl 1,3-dicarboxylate-propanol, using two different methods: use of microwave irradiation in the presence of potassium carbonate and heating in the absence of solvent. The use of heating in the absence of solvent constitutes a novel and efficient method for the synthesis of 1,2,3-oxadiazoles. The heterocycles 49a-e and 53a-e were obtained in moderate yields (40-65%). The 1,3-bis (5-aryl-1,2,4-oxadiazol-3-yl) propan-2-ol (49a-e) were used to carry out Ferrier’s rearrangement. Reaction of these alcohols individually with tri-O-acetyl-D-glucal 17 gave the 2,3-unsaturated O-glycosides 54a–e. In toxicity tests on Artemia saline these compounds (49a-e) have satisfactory results, high toxicity (LD50 ˂ 125 ug / ml) demonstrating that the compounds are promising and may have broad and diverse biological activity. The products were identified using both analytical and spectral data (IV, 1H and 13C NMR) and all compounds are in full agreement with the proposed structure.