Tandem Thien- and Benzannulations of alpha-Alkenoyl-alpha-alkynyl Ketene Dithioacetals with Cyanoacetates: Synthesis of Functionalized Benzo[b]thiophenes

摘要

A novel domino annulation strategy for the construction of benzo[b]thiophenes has been developed. In the presence of Cs2CO3 and Ag2CO3, a wide range of alpha-alkenoyl-alpha-alkynyl ketene dithioacetals readily react with cyanoacetates in CH3CN at 110 degrees C under N-2 to afford multisubstituted benzo[b]thiophenes efficiently via tandem thien- and benzannulations. A plausible mechanism is also proposed.