catalytic hydrogenation and hydrolysis. The separation of the mixture into threo-β-methyl-DL-leucine and erythro-β-methyl-DL-leucine was mainly achieved by fractional crystallization from water. The resolution of each diastereoisomer was also accomplished through salt-formation with (−)- and (+)-ephedrine alternately before or after the methylation of the amino group. The specific rotation and the NMR
通过 2-苄基-4(5H)-
咪唑酮与
甲基异丙基酮缩合,然后催化氢化和
水解,合成了外消旋 β-甲基亮
氨酸的非对映异构混合物。将混合物分离为苏式-β-甲基-
DL-亮氨酸和赤型-β-甲基-
DL-亮氨酸主要是通过从
水中分步结晶来实现的。每个非对映异构体的拆分也通过在
氨基甲基化之前或之后交替与 (-)- 和 (+)-
麻黄碱形成盐来完成。一种异构体苏式-N,β-二甲基-
L-亮氨酸的比旋光度和NMR 和IR 光谱与从自然界中分离的二甲基亮
氨酸报道的那些非常一致。