Diketopiperazine forming dipeptidyl linker

Abstract

The invention relates to a method for homogeneous solution phase peptide synthesis (HSPPS) of a N-terminal peptide fragment PEP-N and a C-terminal peptide fragment C-PEP, with C-PEP carrying a specific diketopiperazine (DKP) comprising C-terminal protecting group, which contains a handle group HG, with HG being connected to the C-terminus of the peptide fragment; thereby this specific DKP comprising C-terminal protecting group can be selectively cleaved from the peptide as a conventionally used C-terminal protecting group. By the use of this DKP and HG comprising C-terminal protecting group, certain process steps in convergent peptide synthesis based on a combination of HSPPS and solid phase peptide synthesis (SPPS) can be avoided. The invention relates further to a method for the preparation of such specifically protected fragment C-PEP by SPPS by using a linker comprising a specific dipeptide and HG for connecting the growing peptide chain to the resin, which linker forms said DKP group, when the peptide fragment C-PEP is cleaved from the supporting resin; and further to the intermediates of the preparation method.