Homogeneous Hydrogenation of Tri‐ and Tetrasubstituted Olefins: Comparison of Iridium‐Phospinooxazoline [Ir‐PHOX] Complexes and Crabtree Catalysts with Hexafluorophosphate (PF
<sub>6</sub>
) and Tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (BAr
<sub>F</sub>
) as Counterions
作者:Bettina Wüstenberg、Andreas Pfaltz
DOI:10.1002/adsc.200700438
日期:2008.1.4
conversion was observed. The productivity of the Crabtree catalyst could be strongly increased by replacing the hexafluorophosphate anion with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. In one case, in the hydrogenation of a tetraalkyl-substituted CC bond, [Ir(Py)(PCy3)(COD)]BArF gave higher conversion than catalyst 11. However, with several other substrates complex 11 proved to be superior.
具有两个非手性膦-恶唑啉(PHOX)配体的铱配合物可从市售的苯恶唑啉开始分两步轻松制备。具有四[3,5-双(三氟甲基)苯基]硼酸酯(BAr F)作为抗衡离子的空气稳定的络合物在一定范围的三和四取代的烯烃的氢化反应中显示出高反应活性。衍生自二环己基膦基恶唑啉配体的铱配合物(11)可获得最佳结果,该配合物在恶唑啉环中不带有其他取代基。对于几种底物,使用Crabtree催化剂的转化率很低,[Ir(Py)(PCy 3)(COD)] PF 6,观察到完全转化。通过用四[3,5-双(三氟甲基)苯基]硼酸酯代替六氟磷酸根阴离子,可以大大提高Crabtree催化剂的生产率。在一种情况下,在四烷基取代的CC键的氢化中,[Ir(Py)(PCy 3)(COD)] BAr F的转化率高于催化剂11。但是,对于其他几种基材,复合物11被证明是优异的。