Enantioselective Total Syntheses of Leuconolam-Leuconoxine-Mersicarpine Group Monoterpene Indole Alkaloids

A unified strategy allowing enantioselective total syntheses of (-)-mersicarpine, (-)-scholarisine G, (+)-melodinine E, (-)-leuconoxine, and (-)-leuconolam from a common cyclohexenone derivative was reported. The Suzuki-Miyaura reaction was used to couple two simple fragments incorporating the key elements for total synthesis, and unprecedented oxidation/reduction/cyclization processes were developed that converted the substituted cyclohexenone to either a mersicarpine or leuconoxine skeleton. In a reverse biomimetic synthesis fashion, (+)-melodinine E was converted to (-)-leuconolam under acidic conditions.