Abstract
3,4-Bis[2-(methyl-phenyl-oxophosphanyl)-ethyl]phenyl-phosphanyl}pyrrolidines have been synthesized by Michael Addition from the corresponding methyl-phenyl-vinyl-phosphane oxides and 3,4-bis(phenylphosphino)pyrrolidines. For purification of the ligands palladium complexes were used and with the enantiomerically pure ligands Rh complexes have been prepared. The catalyst has 6 stereogenic centers. In the hydrogenation of Z-α-acetamidocinnamic acid all six stereogenic centers have an influence on the enantioselectivity. The influence is strongest from the C stereocenters of the pyrrolidine ring. Less important are the stereogenic centers on the coordinated P atoms. The influence of the stereocenters on the non-coordinated P = O groups is the least, but it is not negligible. The ee values obtained with the ligands containing P = O groups are much lower than those obtained with ligands which are substituted only with aryl groups. Ketones are hydrogenated with only low ee’s.
《摘要》
3,4-双[2-(甲基苯基氧代磷基)-乙基]苯基磷基}吡咯烷已通过从相应的甲基苯基乙烯磷氧化物和3,4-双(苯基磷基)吡咯烷的Michael加成合成。为了纯化配体,使用了钯配合物,并利用对映纯配体制备了Rh配合物。该催化剂有6个立体异构中心。在对Z-α-乙酰基肉桂酸的氢化反应中,所有六个立体异构中心对对映选择性产生影响。吡咯烷环的C立体中心对影响最大,配位的P原子上的立体中心较不重要。对非配位的P = O基团的立体中心的影响最小,但并非可以忽略。含有P = O基团的配体获得的ee值远低于仅含芳基基团的配体获得的值。酮类只有低ee值被氢化。