Organocatalytic Asymmetric Robinson Annulation of α,β-Unsaturated Aldehydes: Applications to the Total Synthesis of (+)-Palitantin
作者:Bor-Cherng Hong、Ming-Fun Wu、Hsing-Chang Tseng、Guo-Fong Huang、Cheng-Feng Su、Ju-Hsiou Liao
DOI:10.1021/jo701477v
日期:2007.10.1
The highly enantioselective organocatalytic Robinson annulation of α,β-unsaturated aldehydes was achieved, catalyzed by l-proline and trialkylamines and providing the formal [4 + 2] cycloaddition adducts. Additionally, in some examples in the catalysis with diarylpyrrolinol silyl ethers, the reactions afforded the [4 + 2] adducts with high enantioselectivity (>99.5% ee). The structure of the adduct
通过1-脯氨酸和三烷基胺的催化,获得了高度对映选择性的α,β-不饱和醛有机罗宾逊环合反应,并提供了正式的[4 + 2]环加成产物。另外,在用二芳基吡咯啉醇甲硅烷基醚催化的一些实例中,反应提供了具有高对映选择性(> 99.5%ee)的[4 + 2]加合物。由3-甲基丁-2-烯醛与(E)-3-(2-硝基苯基)丙烯醛的反应获得的加合物的结构通过X射线分析确认。研究了某些[4 + 2]环加合物的绝对构型,并将该方法应用于合成(+)-palantantin。