Hydration and Intramolecular Cyclization of Homopropargyl Sulfonamide Derivatives Catalyzed by Silver Hexafluoroantimonate(V): Synthesis of Structurally Diverse 2,3-Dihydro-1H-Pyrroles

We have developed an efficient, simple protocol for synthesis of structurally diverse functionalized 2,3-dihydro-1H-pyrroles by hydration and intramolecular cyclization of homopropargyl sulfonamide derivatives. Mechanistic experiments revealed that the sulfonamide nitrogen participated in the hydration reaction by chelating the Ag atom of the catalyst to assist in the formation of the hydration intermediate. The protocol accommodated a wide range of substrates and was used for a formal synthesis of (S)-nicotine.