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.