Systematic Evaluation of Substituted Cyclopentadienyl Ruthenium Complexes, [(η<sup>5</sup>-C<sub>5</sub>Me<i>n</i>H5−<i>n</i>)RuCl(cod)], for Catalytic Cycloadditions of Diynes
作者:Yoshihiko Yamamoto、Ken Yamashita、Yu Harada
DOI:10.1002/asia.200900531
日期:2010.4.1
to 10 % conversion) of the cycloaddition was then measured using 1H NMR spectroscopy. The initial rate is found to decrease as the number of methyl substituents increases. According to these results, we assumed that the optimum catalytic performance exhibited by the 1,2,4‐trimethylcyclopentadienyl complex can be attributed to its robustness under the catalytic cycloaddition conditions. The steric and
一系列的η 5个-cyclopentadienylruthenium络合物,[(η 5 -C 5我ñ ħ 5- Ñ)的RuCl(COD)](COD = 1,5-环辛二烯),被评估作为催化剂用于的1,6-环加成二炔与炔烃。结果,我们意外地发现带有1,2,4-Me 3的复合物就大体积二碘二炔与乙炔的环加成而言,就周转数(TON)而言,Cp配体是最有效的催化剂,记录的最高TON为970,负载量为0.1 mol%。为了深入了解此结果,我们通过循环伏安分析评估了所有配合物的电子富集度,这表明钌中心的电子密度随Cp'配体上甲基取代的增加而增加。然后使用1测量环加成反应的初始速率(最高10%的转化率)1 H NMR光谱。发现初始速率随着甲基取代基数量的增加而降低。根据这些结果,我们假设1,2,4-三甲基环戊二烯基配合物表现出的最佳催化性能可归因于其在催化环加成条件下的稳健性。还根据不对称二炔的环加成的区域选择性和1