Síntese e estudo do mecanismo de formação de 2,3-di-hidrobenzofuranos a partir de 2-alil-fenóis e n-bromo-succinimida

Abstract

Oxigenated heterocycles are important compounds in organic chemistry. Among these stand out the class of 2,3-dihydrobenzofurans. At the same time, the presence of a bond carbon-halogen adds value to the substance for the possibility of later funcionalization or use as building-blocks in synthesis of more complex substances. The development of methodologies for halogenation is necessary to obtain selective methods with low environmental impact within the proposed objective. Some advantages of the utilization of N-haloamides in this kind of transformation are the good selectivity and safety. In this work, a method for the synthesis of 2,3-dihydrobenzofuran with electron-donation or electron-withdrawing substituents was developed using acetone or dicloromethane. N-bromosuccinimide was used as the halenium ion source and acetic acid and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalysts. The mecanistic estudy shows that the halogen transfer species is acetyl hypobromite (AcOBr). Nine unknown 2-bromometyl-2,3-dihydrobenzofurans compounds were obtained in 30-83% yields.