A stereoselective metal-mediated cycloaromatization of chiral conjugated dienynes and enediynes is described. For dienyne cycloaromatization, placement of the carbon stereocenter in the allylic position gives the highest diastereomeric ratios (dr). The observed stereoselectivity depends on the steric bulk of the alkyne substituent, as replacing a propargylic methyl for trimethylsilyl increases the dr from 56:44 to 80:20. For both enediyne and dienyne substrates, [(η⁵-C₅Me₅)Ru(NCMe)₃]PF₆ exhibits greater diastereoselectivity than does [(η⁵-C₅H₅)Ru(NCMe)₃]PF₆. For the same chiral enediyne substrate, [(η⁵-C₅Me₅)Ru(NCMe)₃]PF₆ generates a 4:1 ratio of diastereomeric arene products, whereas both [(η⁵-C₅Me₄CF₃)Ru(NCMe)₃]PF₆ and [(η⁵-C₅H₅)Ru(NCMe)₃]PF₆ generate a 1:1 product mixture, indicative of a significant electronic influence of the ancillary ligand on diastereoselectivity. X-ray structure determination of several isolated ruthenium arene diastereomers confirms the assigned relative stereochemistry for the major and minor stereoisomeric metal arene products. Arene-binding experiments demonstrate that the observed stereoselectivity does not involve complexation of free arene by ruthenium.

中文翻译：

---

η的立体选择性合成⁶经由金属触发伯格曼与Hopf Cycloaromatizations -Arene钌（II）配合物

描述了手性共轭二烯和烯二炔的立体选择性金属介导的环芳构化。对于二烯炔环芳构化，将碳立构中心置于烯丙基位置可得到最高的非对映异构体比率（dr）。观察到的立体选择性取决于炔烃取代基的空间体积，因为用炔丙基甲基代替三甲基甲硅烷基会使dr从56:44增加到80:20。对于这两种烯二炔和dienyne底物，[（η ⁵ -C ₅我₅）的Ru（NCMe）₃ ] PF ₆表现出较大的非对映选择性不小于[（η ⁵ -C ₅ H ^ ₅）的Ru（NCMe）₃ ] PF ₆。出于相同的手性烯二炔基，[（η ⁵ -C ₅我₅）的Ru（NCMe）₃ ] PF ₆产生一个4：1的比例的非对映体产品的芳烃，而这两个[（η ⁵ -C ₅我₄ CF ₃）的Ru（NCMe）₃ ] PF ₆和[（η ⁵ -C ₅ H ^ ₅）的Ru（NCMe）₃ ] PF ₆生成1：1的产物混合物，表明辅助配体对非对映选择性具有重要的电子影响。几种分离的钌芳烃非对映异构体的X射线结构测定证实了主要和次要立体异构金属芳烃产品的指定相对立体化学。芳烃结合实验表明，观察到的立体选择性不涉及钌与游离芳烃的络合。