Copper‐Catalyzed, CAN‐Promoted Selenocyclization of 2‑Vinyloxy Arylalkynes via C(sp ² )–O Bond Cleavage

ABSTRACT An efficient and economical copper‐catalyzed selenocyclization of 2‐vinyloxyarylalkynes for the construction of valuable selenobenzofuran derivatives via C(sp 2 )─O bond cleavage was developed. The reaction employs an inexpensive CuI/1,10‐phenanthroline catalytic system and CAN as the oxidant, proceeding smoothly under mild conditions in ethanol and under an air atmosphere. The protocol avoids the use of precious metals or stoichiometric metal reagents and exhibits broad functional‐group tolerance. It is compatible with a variety of substituted arylalkyne substrates and aryl/alkyl diselenides, and can be extended to 2‐alkynylphenols, 2‐alkynylanisoles, as well as to the synthesis of tellurobenzofuran analogues. Gram‐scale experiment confirms the scalability of the method. Mechanistic studies suggest that the transformation likely proceeds through steps involving the generation of oxidative C─O bond cleavage, copper‐catalyzed cycle, and subsequent electrophilic cyclization. This work provides a convenient and practical new approach for the efficient synthesis of selenium‐containing heterocycles.