The Enantioselective Synthesis of Eburnamonine, Eucophylline, and 16′‐<i>epi</i>‐Leucophyllidine
Christopher E. Reimann, Aurapat Ngamnithiporn, Kohei Hayashida, Daisuke Saito, Katerina M. Korch, Brian M. Stoltz
Abstract
A synthetic approach to the heterodimeric bisindole alkaloid leucophyllidine is disclosed herein. An enantioenriched lactam building block, synthesized through palladium-catalyzed asymmetric allylic alkylation, served as the precursor to both hemispheres. The eburnamonine-derived fragment was synthesized through a Bischler-Napieralski/hydrogenation approach, while the eucophylline-derived fragment was synthesized by Friedländer quinoline synthesis and two sequential C-H functionalization steps. A convergent Stille coupling and phenol-directed hydrogenation united the two monomeric fragments to afford 16'-epi-leucophyllidine in 21 steps from commercial material.