Efficient Synthesis of 2,5‐Disubstituted Chalcogenophenes by a One‐pot, Stepwise Glaser Coupling – Cycloaddition Sequence

A mild and efficient method for the synthesis of 2,5‐disubstituted chalcogenophenes is reported. This method involves two steps of reactions via one‐pot approach by employing commercially available and cost‐effective alkynes and element chalcogen. Further, by using LiNH 2 as the promoter and DMSO/EtOH as the solvent, Cu‐catalyzed Glaser coupling‐cycloaddition processes are dramatically enhanced that a diverse range of chalcogenophenes can be obtained in good to excellent yields under mild conditions. Controlled experiments show that trisulfur radical anion (S3⋅ − ) is the key intermediate and DMSO/EtOH serves as the hydrogen source, while alcohol may facilitate the transition state.