Copper‐Catalyzed Three‐Component Cascade Reaction of Azomethine Imines, Alkynes, and Diselenides

A copper‐catalyzed three‐component cascade reaction of azomethine imines, alkynes, and diselenides has been developed for the synthesis of selenated N , N′ ‐bicyclic pyrazolines. This protocol integrates selenation with 1,3‐dipolar cycloaddition in a one‐pot reaction, featuring a broad substrate scope, excellent regioselectivity, and high atomic economy. Mechanistic studies indicate that the reaction proceeds via two pathways: 1,3‐dipolar cycloaddition of selenoalkynes with azomethine imines and selenation of cuprate‐pyrazoline.