Efficient synthesis of 2-aminothiophenes with ionic liquids catalyzed Gewald reactions

Abstract

Herein we report an efficient ionic liquid-catalyzed Gewald reaction for the synthesis of 2-aminothiophenes from 2,5-dihydroxy-1,4-dithiane and substituted activated nitriles. Under the reaction conditions of [HOEmim]PF₆:H₂O at a ratio of 0.4:0.1, a series of 2-aminothiophenes were synthesized with moderate to good yields (55–98.1%). Electrostatic potential surface map elucidated the promoting effect of an optimal water content on the reaction dynamics. Moreover, the catalytic system exhibited excellent recyclability and reusability, maintaining its activity without significant loss even after ten cycles.