A Concise Total Synthesis of (−)-Mesembrine

2016-10-10T00:00:00Z (GMT) by Lu-Ning Wang Qi Cui Zhi-Xiang Yu
A concise total synthesis of mesembrine (four steps from known compound) was achieved both racemically and asymmetrically. Two key reactions were used here. One is the Rh­(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropane <b>3c</b> and CO. The other one is Buchwald’s Pd-catalyzed coupling reaction that coupled β,γ-cyclohexenone <b>2c</b> with aryl bromide <b>5</b> (using dppe ligand for racemic or (<i>S</i>)-Antphos ligand for asymmetric synthesis) to give γ,γ-disubstituted α,β-cyclohexenone <b>1c</b>. Finally, aza-Michael addition converted <b>1c</b> to mesembrine.