L-Phenylalanine,L-valine and L-leucine were used to prepare the corresponding NCAs.

• 用L-苯丙氨酸；L-缬氨酸；L-亮氨酸制得相应的N-羧酸内酸酐；并分别与二乙胺；叔丁胺；异丙胺；正丁胺反应.