Synthesis and Rearrangement of Pyrrolyl Sulfides and Sulfones

Article abstract of DOI:10.1021/jo00140a016

A general synthesis of 3-pyrrolyl sulfides was developed on the basis of the triphenylphosphine-iodine-sodium iodide reduction of the sulfoxides, which in turn were obtained by the acid-mediated rearrangement of the corresponding 2-sulfinylpyrroles.Methods were also devised for the reduction of 2-(alkylsulfinyl)pyrroles to the sulfides. 2-Pyrrolyl and 3-pyrrolyl sulfides were shown to undergo acid-induced equilibration under mild conditions.With trifluoroacetic acid in dichloromethane solution, at room temperature, the equilibrium always was in favor of the 2-isomer and the interconversion appeared to be intramolecular. 2-(Methylsulfonyl)pyrrole and 2-(phenylsulfonyl)pyrrole were transformed into the 3-substituted isomers when heated under strongly acidic conditions.