Cyclization of Diaryl(hetaryl)alkynes under Selenobromination Conditions: Regioselectivity and Mechanistic Studies

Abstract

Abstract The cyclization of substituted diaryl(hetaryl)alkynes with in‐situ‐prepared SeBr 4 has been achieved. The use of an alkene additive as a bromine scavenger gives simple access to functionalized benzo[ b ]selenophene and selenophenothiophene derivatives from commercially available or easily accessible starting materials. The reactions can be performed in air without the use of moisture‐sensitive reagents, dry solvents, or an inert atmosphere. Mechanistic studies confirmed a regioselective anti 1,2‐addition in the selenobromination step, and a subsequent electrophilic substitution in the aromatic ring to complete the cyclization.