Palladium-Catalyzed Multiple Arylation of Thiophenes
摘要:
Secondary 2-thiophenecarboxamides efficiently undergo unique triarylation accompanied by formal decarbamoylation under palladium catalysis. 3-Substituted thiophenes, especially having an electron-withdrawing group, can also be triarylated.
The first palladium‐catalyzed direct benzylic C(sp3)−H chalcogenation with diaryl disulfides and diphenyl diselenide has been established. The coupling reaction proceeds between the thioether radical and palladiumcycle intermediate. Picolinamide serves as an excellent directing group for the C−H activation of benzylic C(sp3)−H and can be easily removed. The current protocol exhibits a relatively