Catalytic Asymmetric Total Synthesis of Schibitubin G and Revision of Its Absolute Configuration

The first total syntheses of dibenzylbutane-type lignan shibitubin G, and of its enantiomer, were achieved from commercially available vanillin. A key catalytic asymmetric Michael addition reaction was used to introduce the C8′ chiral center of this natural product. The absolute configuration of natural schibitubin G was revised to 8′S based on the X-ray crystallographic analysis of 14, and by comparing optical rotations of both synthetic samples with that of natural schibitubin G.以商用香草醛为起始原料，首次完成了二苄基丁烷型木脂素（dibenzylbutane-type lignan）shibitubin G及其对映体的全合成。反应中借助关键的催化不对称迈克尔加成反应，引入该天然产物的C8′手性中心。通过对化合物14的X射线晶体衍射分析，并对比两组合成样品与天然schibitubin G的旋光度，将天然schibitubin G的绝对构型修正为8′S。