Gold-Catalyzed Domino Aminocyclization/1,3-Sulfonyl Migration of N-Substituted N-Sulfonyl-aminobut-3-yn-2-ols to 1-Substituted 3-Sulfonyl-1H-pyrroles

A method to prepare 1-substituted 3-sulfonyl-1H-pyrroles efficiently that relies on the gold(I)-catalyzed cycloisomerization of N-substituted N-sulfonyl-aminobut-3-yn-2-ols is described. The method was shown to be applicable to a broad range of 1,7-enyne alcohols containing electron-withdrawing, electron-donating, and sterically demanding substrate combinations. The mechanism is suggested to involve activation of the propargylic alcohol by the Au(I) catalyst, which causes the intramolecular nucleophilic addition of the sulfonamide unit to the alkyne moiety. The resulting nitrogen-containing heterocyclic intermediate undergoes dehydration and deaurative 1,3-sulfonyl migration, a process that remains rare in gold catalysis, to give the aromatic nitrogen-containing product.