Asymmetric hydrogenation of indene carboxylic acids: stereochemistry of hydrogen addition
作者:K Borszeky、T Mallat、A Baiker
DOI:10.1016/s0957-4166(99)00576-5
日期:1999.12
The stereochemistry of hydrogen addition to α,β-unsaturated carboxylic acids was studied by means of hydrogenation of indene carboxylic acids and their derivatives. Experiments were carried out over Pd/Al2O3 in the presence and absence of cinchonidine as a chiral modifier. In all cases hydrogenation occurred via bottom side syn addition of two hydrogen atoms to the chemisorbed substrate. Formation
通过氢化茚羧酸及其衍生物,研究了向α,β-不饱和羧酸加氢的立体化学。在存在和不存在辛可尼丁作为手性改性剂的情况下,在Pd / Al 2 O 3上进行实验。在所有情况下,氢化都是通过将两个氢原子向化学吸附的底物进行底侧顺式加成而发生的。反式的形成由于底物中的CC键异构化以及空间位置不利的不饱和分子的吸附和氢化,可观察到高达72%的异构体。N碱促进了“颠倒”位置的吸附。3-甲基茚-2-羧酸的氢化提供了高达45%的ee。由于Pd在CC键迁移中具有很高的活性,只有在异构化可忽略不计的情况下,才能获得良好的ee。