Concise Syntheses of Lycojapomine Alkaloids Enabled by Radical Dearomatization of a Pyrrole

Abstract

We disclose the first total syntheses of the complex alkaloids Lycojapomine A and B. Our synthetic strategy is built on a dearomatization and stepwise functionalization of a pyrrole starting material, constructing the three-dimensional structure of the target around it. This is enabled by a high-yielding photoinduced primary radical addition from the N-hydroxy phthalimide ester and a subsequent silver-catalyzed 5-endo-dig and Aza-silyl-Prins annulation cascade. Divergent control over an aldol reaction yields both Lycojapomines A and B in an efficient manner, without the need for any excess protecting groups.