作者:Kaoru Harada、Toratane Munegumi
DOI:10.1246/bcsj.56.2774
日期:1983.9
N-[(R)-Lactoyl]-(S)-amino acid isobutyl esters were obtained with a diastereoisomeric purity up to 34%, through the catalytic hydrogenations of N-pyruvoyl-(S)-amino acid (alanine, valine, and leucine) isobutyl esters over palladium on charcoal. It was found that a linear correlation exists between the dielectric constant of the solvent and the diastereoisomeric purity of the product obtained by catalytic hydrogenation. The ratio of N-[(S)-lactoyl]-(S)-amino acid isobutyl ester to N-[(R)-lactoyl]-(S)-amino acid isobutyl ester increased with the decrease of the dielectric constant of the solvent. This solvent effect could be explained by the chelation mechanism. The temperature effect on the asymmetric catalytic hydrogenation was also studied.
N-[(R)-乳酸酰]-(S)-氨基酸异丁酯通过在炭黑上催化氢化N-丙酮酸-(S)-氨基酸(丙氨酸、缬氨酸和亮氨酸)异丁酯获得,非对映体纯度高达34%。研究发现,溶剂的介电常数与催化氢化生成产品的非对映体纯度之间存在线性相关关系。N-[(S)-乳酸酰]-(S)-氨基酸异丁酯与N-[(R)-乳酸酰]-(S)-氨基酸异丁酯的比例随着溶剂介电常数的降低而增加。该溶剂效应可以通过螯合作用机制进行解释。同时,对不对称催化氢化的温度效应也进行了研究。