Absolute structure of shoreaketone: a rotational isomeric resveratrol tetramer in Dipterocarpaceaeous plants
作者:Tetsuro Ito、Masayoshi Oyama、Hironao Sajiki、Ryuichi Sawa、Yoshikazu Takahashi、Munekazu Iinuma
DOI:10.1016/j.tet.2012.02.036
日期:2012.4
asymmetric carbons and a framework of fused heptacyclic ring system including a spiro ring and an α,β-unsaturated carbonyl group that has not been reported in any other natural product. NMR experiments using shoreaketone indicate the presence of two conformers due to restricted rotation of a C–C bond in solution. The complex stereochemistry is due to its skeleton, 10 asymmetric carbons, and a chiral
甲旋转异构shoreaketone(1:),鉴定为白藜芦醇四聚体的骨架构件,由三种Dipterocarpaceaeous植物分离娑罗滇水金凤,娑罗栗,和Vateria籼稻。通过包括NMR实验在内的光谱分析阐明了该结构,并基于圆二色性数据确定了它们的绝对构型。肖内酮具有10个不对称碳原子和稠合的七环系统骨架,其中包括螺环和α,β-不饱和羰基,在任何其他天然产物中均未见报道。使用肖内酮的NMR实验表明,由于溶液中C–C键的旋转受限,因此存在两个构象异构体。复杂的立体化学是由于其骨架,10个不对称碳原子和手性轴所致。通过变温NMR,ROESY(骨架转化)研究了旋转异构体类苯乙烯类化合物的构象。确认岸酮(1)的两个构象体共存为1a。在图1b和图1b中,其中二芳基-二氢苯并呋喃部分(单元1B)分别在环戊烷环(单元1A)的平面下方或上方延伸。