Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels–Alder Reaction

An enantio- and stereoselective
construction of the atisane scaffold
via organocatalytic intramolecular Michael reaction and Diels–Alder
reaction is described. The organocatalytic intramolecular Michael
reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic
centers. Use of the chiral secondary amine bearing thiourea with benzoic
acid as additive is the key to obtaining the desired product with
excellent ee in synthetically acceptable yield. The prepared chiral
building block has been successfully converted to the compound including
the atisane scaffold via the highly stereoselective intramolecular
Diels–Alder reaction.

本文报道了一种通过有机催化分子内迈克尔反应与狄尔斯-阿尔德反应(Diels–Alder reaction)构建atisane骨架(atisane scaffold)的对映选择性与立体选择性合成方法。研究表明，该有机催化分子内迈克尔反应可立体选择性地生成包含全碳季碳中心与叔碳手性中心的反式立体二元单元。以携带硫脲基团的手性二级胺为催化剂、苯甲酸为添加剂的催化体系，是获得具有优异对映体过量(ee)值且收率符合合成要求的目标产物的关键。通过高立体选择性分子内狄尔斯-阿尔德反应，可将所制备的手性合成砌块顺利转化为含有atisane骨架的目标化合物。