Solid-phase peptide synthesis in the reverse (N --> C) direction.

[reaction: see text] A new strategy for SPPS in the reverse direction based on the use of 2-Cl-trityl resin, an allyl ester as the temporary protecting group, and Cu(OBt)(2)/DIPCDI or HATU/DIEA as the coupling method is described. These conditions ensure good yields with minimal racemization of the C-terminal residue.