To overcome this obstacle, we assembled peptide 6 on the HMPB linker resin and prepared the ethyl thioester in solution using PyBOP/EtSH (Scheme 2). Assembly of Tau(77-118) 8 on Fmoc-MeDbz-Rink Amide Chem-Matrix resin proceeded smoothly, as well as activation of the MeDbz linker (this peptide contains a N-terminal thiazolidine as a cysteine protective group for orthogonal protection in NCL). Finally, Tau(41-76) 7 and Tau(119-156) 9 were assembled in excellent yields on the Fmoc-Dbz(Boc)-Rink Amide Chem-Matrix resin, and the N-terminal cysteines were protected as ligation compatible disulfides.