Toward a total synthesis of the stemofoline alkaloids: Advancement of a 1,3-dipolar cycloaddition strategy.

Novel, intramolecular 1,3-dipolar cycloadditions of azomethine ylides have been applied to the synthesis of functionalized core structures of the stemofoline alkaloids. In an effort to maximize the efficiency of this key transformation in the context of an eventual total synthesis of these complex natural products, a number of strategic modifications to the cycloaddition substrate were investigated. These collective efforts have provided useful insights into the operative, regiochemical control elements for 1,3-dipolar cycloadditions leading to stemofoline alkaloids. A potential intermediate in the synthesis of these alkaloids was prepared.