化学酶法合成光学纯亮氨酸

用化学酶法合成L-亮氨酸，先在PdCl2/PPh3/LiBr/H2SO4催化体系作用下，异戊醛酰胺羰基化合成消旋的N-乙酰基亮氨酸；然后在酰基转移酶催化下水解，得到L-亮氨酸和N-乙酰基-D-亮氨酸．文中对酰胺羰基化反应条件进行了优化，分离得到消旋N-乙酰基亮氨酸产率为66．4％．经酶对映选择地水解后得L-亮氨酸，产率为41％，产物L-亮氨酸经衍生化后由气相色谱测定其光学纯度达99％ee．

Chemoenzymatic Synthesis of Enantiomerically Pure Leucine

In this study enantiomerically L-leucine was prepared by chemoenzymatic synthesis.In the first step of the reaction sequence the racemic N-acetylleucine was prepared by amidocarbonylation from isovaleraldehyde,acetamide and carbon monoxide in the presence of PdCl_2/PPh_3/LiBr/H_2SO_4 catalyst system.Subsequently L-leucine andD-N-acetylleucine were obtained by the acylase-catalyzed hydrolysis.The amidocarbonylation reaction conditions were optimized and 66.4% isolated yield of racemic N-acetylleucine were obtained.L-leucine was obtained from the enzymatic enantioselective hydrolysis of racemic N-acetylleucine in a yield of 41%,and its derivative enantiomeric purity determined by G.C was 99% ee.