PROBLEM TO BE SOLVED : To provide new peptide modifiers and methods for preparation thereof. SOLUTION : The present invention relates to peptide modifier compounds of a formula (1), or a salt thereof, where : a is an integer from 1 to 10, more preferably from 1 to 3; b is an integer from 0 to 7; Z is a terminal group and Y is a bivalent group. Further aspects of the invention relate to intermediates in preparation of compounds of the formula (1), and use of compounds of the formula 1 in synthesis of peptide derivatives. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT