Pentapeptide synthesis

A method of synthesizing commercial quantities of the pentapeptide L-aspartyl-L-seryl-L-aspartyl-L-prolyl-L-arginine, and salts or solvates thereof, e.g., the hydrochloride or acetate salt or water solvate, compounds useful in pharmaceutical compositions for the treatment of allergic conditions, is disclosed, as are novel intermediate compounds produced in the course of the synthesis.