Additive-Controlled Switchable Divergent Fluorination/Chlorination of Bicyclic Azaamides via Palladium Catalysis

A silver-controlled switchable halogenation of bicyclic azaamides via palladium catalysis has been developed, exhibiting broad functional group tolerance. The switchable divergent reactivity between fluorination and chlorination is dependent on the additive. The presence of Ag2CO3 promotes fluorination through activation of an electrophilic fluorinating agent, whereas its absence selectively favors chlorination via activation of the DCE solvent as a chlorine source. Comprehensive experimental and mechanistic investigations elucidate the reaction pathway and reveal the key factors governing this switchable divergent outcome.