A Consecutive Four‐Component Synthesis of Polysubstituted Thiophenes in Aqueous Medium

An efficient and straightforward four‐component synthesis of mono‐, bi‐ and tricyclic thiophenes from C–C + C + C + S atom fragments from 1,3‐dicarbonyl compounds, aldehydes, activated methylene halides and elemental sulfur in aqueous medium is described. Arylidene‐1,3‐dicarbonyls, N ‐phenacylpyridinium bromides/ N ‐( p ‐nitrobenzyl)pyridinium chloride, pyridinium ylides and 2,3‐dihydrofurans are believed to be the key intermediates of these consecutive transformations. This synthetic strategy provides a potential route to the construction of a library of highly substituted thiophenes with a large substrate scope in good‐to‐excellent yields.