Total solid-phase synthesis of 1,4,7,10-tetraazacyclododecane-N,N', N'',N'''-tetraacetic acid-functionalized peptides for radioimmunotherapy.

A convenient approach to the functionalization of peptides with the macrocyclic 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) moiety has been developed. Protected components (using tert-butyl or tert-butyloxycarbonyl groups) of both the peptide and the chelate were assembled on the same solid resin support. Deprotection and cleavage of the resin-bound DOTA-peptides were performed in one step using a trifluoroacetic acid cleavage mixture to yield free DOTA-peptide amides.