A New Class of Substrates for Nucleophilic 5‐ endo ‐trig Cyclization, 2‐Trifluoromethyl‐1‐alkenes: Synthesis of Five‐Membered Hetero‐ and Carbocycles That Bear Fluorinated One‐Carbon Units

Disfavored 5‐ endo ‐trig cyclizations were achieved in 2‐trifluoromethyl‐1‐alkenes with a nucleophilic nitrogen, oxygen, sulfur, or carbon atom through 1) intramolecular S N 2′ reaction with loss of a fluoride ion or 2) intramolecular nucleophilic addition to the vinylic group. This reaction manifold provides a versatile method for the synthesis of indolines, indoles, pyrrolidines, tetrahydrofurans, 2,3‐dihydrobenzo[ b ]thiophenes, tetrahydrothiophenes, and cyclopentanes that bear a fluorinated one‐carbon unit such as a difluoromethylene, difluoromethyl, or trifluoromethyl group.