Reynolds G D, Harding D R, Hancock W S
Int J Pept Protein Res. 1981 Feb;17(2):231-4. doi: 10.1111/j.1399-3011.1981.tb01986.x.
Solution synthesis of Leu-enkephalin has been achieved using the coloured carboxyl protecting p-(p-(dimethylamino)phenylazo)benzyl moiety throughout the synthesis. The intense colour of this protecting group allowed facile purification of protected intermediates on silica gel or ion exchange columns and visualisation on thin-layer chromatography. The chromogenic p-(p-(dimethylamino)phenylazo)benzyl ester group readily withstands successive treatments with 25% trifluoroacetic acid in dichloromethane yet is cleanly removed by catalytic hydrogenation.
在整个合成过程中，使用带色的羧基保护基对-（对-（二甲氨基）苯基偶氮）苄基实现了亮氨酸脑啡肽的溶液合成。该保护基的强烈颜色使得在硅胶柱或离子交换柱上对受保护中间体进行简便纯化成为可能，并且在薄层色谱上易于观察。生色的对-（对-（二甲氨基）苯基偶氮）苄酯基能够轻易经受住二氯甲烷中25%三氟乙酸的连续处理，但通过催化氢化可被干净地除去。
