Base-catalyzed regio- and stereoselective addition of isatins to trifluoromethylated alkynes for preparation of N-alkenylisatins

Abstract

Direct addition of isatins to trifluoromethylated internal alkynes was developed under inorganic base catalysis with simple, mild, and environmentally benign conditions. A series of intended N-alkenylisatins was readily assembled with good functional group compatibility and diversity. Meanwhile, exclusive regio- and stereo-selectivities were achieved to provide the β-adducts with Z configuration only. Taking advantage of its intrinsic versatile reactivity, the N-alkenylisatin product was transformed into useful 2-phenyl-3-(trifluoromethyl)quinoline-4-carboxylates via one-step late-stage derivatization. In addition, a set of control experiments was designed and implemented to shed light on the possible reaction mechanism.