Abstract: Urethane-protected NCAs and MTAs are prepared by reacting an NCA or NTA with a haloformate in an inert diluent, under anhydrous conditions and in the presence of a tertiary nitrogen-containing base having an atom or functional group sufficiently electron rich and positioned relative to the nitrogen of said base so as to render said atom or group capable of complexing with the H--N< group of said N-carboxyanhydride or N-thiocarboxyanhydride but able to generate N-carboxyanhydride or N-thiocarboxyanhydride anionic complexes capable of reacting with the haloformate.

Abstract: A synthetic vaccine is contemplated comprising a peptide residue coupled to one or more alkyl or alkenyl groups of at least 12 carbon atoms or other lipophilic substance wherein said peptide residue contains a sequence of 6 amino acids corresponding to the sequence of such amino acids in a protein antigen or allergen where the greatest local average hydrophilicity of the antigen or allergen is found.