Palladium(II)-Catalyzed Cyclization of Olefinic Tosylamides

摘要

The palladium-catalyzed cyclization of simple olefinic amines, tosylamides, and carboxamides has proven to be a particularly valuable route to a wide variety of nitrogen heterocycles. For example, the cyclization of o-vinylic and o-allylic anilines or their tosyl derivatives by either stoichiometric amounts of palladium(II) salts or catalytic amounts of palladium(II) salts in the presence of benzoquinone as a reoxidant efficiently provides indolesX, We recently reported the palladium-catalyzed conversion of alkenoic acids to unsaturated lactones and enol silanes to enals and enones using a remarkably simple, environmentally attractive catalyst system consisting of 5 mol % Pd(OAc)_2 under an atmosphere of O_2 in DMSO solvent with no additional reoxidants. The recent report of one example of the cyclization of an olefinic tosylamide to an N-allylic tosylamide using this same catalyst system, plus earlier reports of the cyclization of unsaturated tosylamides to N-vinylic tosylamides by other palladium(II) catalyst systems, encourages us to report at this time our unusual results using the Pd(OAc)_2/O_2 catalyst on a variety of simple olefinic tosylamides.