well‐known IMes ligand by substituting the carbenic heterocycle with one and two dimethylamino groups, respectively, were employed for the synthesis of second‐generation Grubbs‐ and Grubbs–Hoveyda‐type ruthenium metathesis precatalysts. Whereas the stability of the complexes was found to depend on the degree of dimethylamino‐substitution and on the type of complex, the backbone‐substitution was shown to
Synthesis of Spiro Ethers by Ring Closing Metathesis
作者:Martin E. Maier、Michael Bugl
DOI:10.1055/s-1998-1943
日期:1998.12
Starting from the cyclic ketones 1 a - d, the dienes 3 a - e were prepared. The ring closing metathesis reaction of these dienes using the Grubbs catalyst 5 provided the corresponding spiro ethers 4 a - e in good yield. Force field calculations indicate that the conformer with the oxygen in axial position is favored.
从环酮 1 a - d 开始,制备二烯 3 a - e。使用格拉布斯催化剂 5 对这些二烯进行闭环偏析反应,可以得到相应的螺醚 4 a - e,收率很高。力场计算表明,氧处于轴向位置的构象更受青睐。
Testing diverse strategies for ruthenium catalyst removal after aqueous homogeneous olefin metathesis
mixtures after aqueous homogeneous olefin metathesis (AHOM) reactions have been probed to address this shortcoming. It was found that elimination of a water-soluble Ru catalyst after AHOM conducted in neat water can be achieved via addition of thiocyanate ions (with or without support of charcoal additive). The developed purification method can make the aqueous metathesis methodology more practical, allowing
传统上,烯烃复分解 (OM) 在有机溶剂中进行,例如二氯甲烷或甲苯。由于近二十年来耐水甚至水溶性钌催化剂的发展,水介质中的 OM 取得了长足的进步。然而,从水中进行的 OM 反应产物中去除钌仍然是一项重大挑战。在目前的工作中,已经探索了在水性均相烯烃复分解 (AHOM) 反应后纯化反应混合物的选定方法,以解决这一缺点。发现在纯水中进行 AHOM 后,水溶性 Ru 催化剂的消除可以通过以下方式实现:添加硫氰酸根离子(有或没有木炭添加剂的支持)。所开发的纯化方法可以使水性复分解方法更实用,从而更容易将废水溶性催化剂与水溶性复分解产物分离。不幸的是,在水/醇混合物中进行的 AHOM 反应的情况下,这种方法不能提供令人满意的结果。为了在后一种情况下分离Ru催化剂,测试了一种利用刺激响应性聚合物的方法,但结果有限。
OLSSON L.-I.; CLAESSON A., SYNTHESIS, 1979, NO 9, 743-745