Síntese de novos derivados 2-aminotiofênicos através da reação de Gewald utilizando produtos naturais como precursores

Abstract

Natural products represent a vast source of molecules with pharmacological potential and serve as a basis for seeking and obtaining of new bioactive substances semi-synthetic and synthetic. Based on this knowledge, the interest for new pharmacologically active substances, resulted in the isolation, extraction and synthesis of various bioactive molecules. The medicinal chemistry uses natural products as template for the synthesis of new molecules that are capable of acting against various diseases that affect the global population. Natural products and bioactive molecules thiophenes are widely cited in the literature. This study evaluated two methods (conventional and ultrasonic) synthesis of new 2-aminotiofenos using as precursors various natural products through Gewald reaction by comparing several variables. 13 reactions were analyzed by varying the solvent, base, temperature, agitation mode, time and number of steps. There was the formation of at least one by-product in all reactions. Among the variables, the seconding most effective were: ultrasonic methodology, the lower temperature and shorter reaction time. The ultrasonic energy reactions conducted more quickly (in less reaction time), forming fewer byproducts of the reaction by magnetic stirring. The temperature variable is also essential to this study, the best results being obtained at lower possible temperature (ambient or ice bath). The isolation of some byproducts of the reactions was carried out, but the 1H NMR analysis allowed to identify neither the desired end product (adduct of Gewald) or intermediate (Knoevenagel adduct). New methodological changes and isolation of other byproducts still need to be carried out to prove the success of the reactions and to obtain new adducts Gewald. This study allowed the start of the optimization of reaction conditions of Gewald reaction using natural products as precursors and assist future work in the area.