Potential and Limitations of Palladium–Cinchona Catalyst for the Enantioselective Hydrogenation of a Hydroxymethylpyrone
作者:W.-R. Huck、T. Mallat、A. Baiker
DOI:10.1006/jcat.2000.2890
日期:2000.7
palladium-catalyzed enantioselective hydrogenation of 4-hydroxy-6-methyl-2-pyrone afforded up to 85% excess to the (S)-enantiomer of the corresponding 5,6-dihydropyrone, under very mild conditions (1 bar, room temperature). This is the highest enantioselectivity achieved so far with chirally modified Pd, demonstrating the potential of this catalyst in the enantioselective hydrogenation of unsaturated compounds
在非常温和的条件下(1巴,室温),钯催化的4-羟基-6-甲基-2-吡喃酮的对映选择性氢化比相应的5,6-二氢吡喃酮的(S)-对映异构体多出85%的过量)。这是迄今为止通过手性修饰的Pd达到的最高对映选择性,证明了该催化剂在不饱和化合物的对映选择性氢化中的潜力。该反应的复杂特征是辛可尼定在反应条件下的稳定性有限,这导致初始对映体过量(ee)随着反应时间的减少而降低。在反应过程中连续进料微量的辛可尼定,可维持较高的初始ee,而底物/改性剂的总摩尔比约为1。20