title: Use of the chromogenic p-(p-(dimethylamino)phenylazo) benzyl (AZ) ester in the synthesis of leu-enkephalin.
abstract: 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.
mesh_terms: D000596:Amino Acids; D001391:Azo Compounds; D002863:Chromogenic Compounds; D004723:Endorphins / Q000138:chemical synthesis*; D004743:Enkephalin, Leucine; D004745:Enkephalins / Q000138:chemical synthesis*
chemical_list: D000596:Amino Acids; D001391:Azo Compounds; D002863:Chromogenic Compounds; D004723:Endorphins; D004745:Enkephalins; D004743:Enkephalin, Leucine