Synthesis and Application of ChiralN-Heterocyclic Carbene–Oxazoline Ligands: Iridium-Catalyzed Enantioselective Hydrogenation
作者:Steve Nanchen、Andreas Pfaltz
DOI:10.1002/chem.200501500
日期:2006.6.2
one compound from each family was characterized by X-ray structure analysis. The two libraries of iridium complexes were successfully tested in the asymmetric hydrogenation of unfunctionalized and functionalized olefins. Enantioselectivities of up to 90 % ee were obtained with trans-alpha-methylstilbene. Upon complexation of imidazolium salt 15 p with R(1) = phenyl, C-H bond activation of the phenyl
合成了带有恶唑啉单元的两个对映体纯的咪唑鎓盐文库。通过在室温下将咪唑鎓盐与NaOtBu和[(eta(4)-cod)IrCl](2)混合在一个步骤中,即可实现咪唑鎓盐的去质子化以及所形成的恶唑啉-卡宾配体与铱(I)的络合。温度。空气稳定的复合物通过快速色谱法纯化。通过二维(2D)NMR方法分析所有复合物,并通过X射线结构分析对每个族的一种化合物进行表征。在未官能化和官能化的烯烃的不对称氢化中成功地测试了两个铱配合物库。用反式-α-甲基sti得到的对映选择性高达90%ee。咪唑鎓盐15 p与R(1)=苯基络合后,苯环的CH键活化产生了铱(III)配合物17,该配合物通过NMR光谱学和X射线结构分析得到了充分表征。络合物17在氢化中被证明是催化惰性的。