Unsaturated sulfoxides in organic synthesis: A new general pyrrole synthesis

Pyrroles have been efficiently synthesised by a three-step reaction sequence. Michael addition of keto esters onto phenyl vinyl sulfoxide followed by Pummerer rearrangement gave the cyclic key intermediate 3. Mercury(II) salt induced carbon-sulfur bond cleavage afforded a 1,4-dicarbonyl equivalent 5. Treatment of the latter with an ammonium salt or a primary amine led to substituted pyrroles.