Roger Adams Laboratory, Department of Chemistry , University of Illinois , Urbana , Illinois 61801 , United States.
J Am Chem Soc. 2018 Mar 14;140(10):3569-3573. doi: 10.1021/jacs.8b01660. Epub 2018 Mar 6.
A sulfenium-ion-initiated, catalytic, enantioselective polyene cyclization is described. Homogeranylarenes and ortho-geranylphenols undergo polycyclization in good yield, diastereoselectivity, and enantioselectivity. The stereodetermining step is the generation of an enantiomerically enriched thiiranium ion from a terminal alkene and a sulfenylating agent in the presence of a chiral Lewis basic catalyst. The use of hexafluoroisopropyl alcohol as the solvent is crucial to obtain good yields. The thioether moiety resulting from the reaction can be subsequently transformed into diverse oxygen and carbon functionality postcyclization. The utility of this method is demonstrated by the enantioselective syntheses of (+)-ferruginol and (+)-hinokiol.
描述了一种由亚磺酰阳离子引发的、催化的、对映选择性的多烯环化反应。偕二芳基萜烯和邻-香叶基苯酚在高产率、非对映选择性和对映选择性下进行多环化反应。立体决定步骤是在手性路易斯碱性催化剂的存在下，从末端烯烃和亚磺酰化剂生成对映体富集的硫𬭩离子。使用六氟异丙醇作为溶剂对于获得良好的产率是至关重要的。反应生成的硫醚部分可以在环化后进一步转化为多种氧和碳官能团。该方法的实用性通过 (+)-ferruginol 和 (+)-hinokiol 的对映选择性合成得到了证明。
