Tertiary Amine-Catalyzed Difluoromethylthiolation of Morita-Baylis-Hillman Carbonates of Isatins with Zard's Trifluoromethylthiolation Reagent

In this paper, we report that a novel tertiary amine-catalyzed [3+2] annulation between Morita-Baylis-Hillman (MBH) carbonates derived from isatins with thiocarbonyl fluoride (F2C=S) in situ generated from Zard's reagent proceeds smoothly under mild conditions, affording difluoro-methylthiolated spirocyclic oxindoles in good to excellent yields. Moreover, the asymmetric variant could be realized with a modified Cinchona alkaloid, giving the desired cyclic adducts in good to excellent yields with good enantioselectivities.