<i>Endo</i>-Selective Enyne Ring-Closing Metathesis Promoted by Stereogenic-at-Mo Monoalkoxide and Monoaryloxide Complexes. Efficient Synthesis of Cyclic Dienes Not Accessible through Reactions with Ru Carbenes
作者:Yeon-Ju Lee、Richard R. Schrock、Amir H. Hoveyda
DOI:10.1021/ja904098h
日期:2009.8.5
Mo-catalyzed reactions afford the endo product exclusively. The efficiency of synthesis of N- and O-containing endo diene heterocycles can be improved significantly through structural modification of Mo catalysts. The modularity of Mo-based monopyrrolides is thus exploited in the identification of the most effective catalyst variants. Through alteration of O-based monodentate ligands, catalysts have been identified
Stereogenic-at-Mo单烷氧化物和单芳基氧化物复合物促进烯炔闭环复分解(RCM)反应,提供具有高选择性(通常> 98:< 2内:外)的相应内产物。所有催化剂都可以原位制备和使用。五元环、六元环和七元环是通过与带有全碳系链以及含有杂原子取代基的烯炔底物反应获得的。新开发的催化方案补充了相关的外选择性 Ru 催化过程。在基于 Ru 的配合物无差别地提供外向和内向产物的情况下,例如当生成四取代的环烯烃时,钼催化反应仅提供内向产物。通过Mo催化剂的结构改性可以显着提高含N和O的内二烯杂环的合成效率。因此,基于钼的单吡咯烷的模块化被用于鉴定最有效的催化剂变体。通过改变基于 O 的单齿配体,已确定催化剂可以提高烯炔 RCM 的效率。通过 X 射线晶体学阐明了三种 Mo 配合物的结构属性。报道了催化对映选择性烯炔 RCM 反应的第一个例子(高达 98:2 的对映体比例和 >98% 的内)。已经鉴定出能够以更高的效率促进烯炔
<i>Endo</i>-Selective Enyne Ring-Closing Metathesis Promoted by Stereogenic-at-W Mono-Pyrrolide Complexes
作者:Yu Zhao、Amir H. Hoveyda、Richard R. Schrock
DOI:10.1021/ol1030525
日期:2011.2.18
The utility of W-alkylidene complexes for enyne ring-closing metathesis is demonstrated in a direct comparison with Mo-based analogs. Tungsten complexes lead to less alkyne oligomerization and higher levels of endo-selectivity and enantioselectivity.