Inter- and Intramolecular Addition/Cyclizations of Sulfonamide Anions with Alkynyliodonium Triflates. Synthesis of Dihydropyrrole, Pyrrole, Indole, and Tosylenamide Heterocycles

The synthesis of dihydropyrroles, pyrroles, and indoles through [3-atom + 2-atom] combination of ethyl or aryl tosylamide anions with phenyl(propynyl)iodonium triflate, and the base-mediated intramolecular bicyclization of alkynyliodonium-bearing tosylamide or tosylimide substrates to furnish bicyclic and tricyclic tosylenamide (-enimide) products, is described. A detailed discussion of the scope, limitations, byproduct formation, and the basis for observed diastereoselectivity is presented.