Solid-phase and solution-phase syntheses of oligomeric guanidines bearing peptide side chains

[reaction: see text] Synthetic strategies for preparing N,N'-bridged oligomeric guanidines bearing peptide side chains both on solid support and in solution are presented. Monomers are prepared from common alpha-amino acids and therefore contain conventionally protected peptide side chains. The side chains include alkyl, aromatic, hydroxyl, amino, carboxylic acid, and amide functional groups. Oligomer elongation utilizes acid-sensitive sulfonyl activated thiourea through the formation of carbodiimide intermediate. With proper preparation of monomers, synthesis of oligomer can be performed in two directions (equivalent to N to C terminal or C to N terminal in a peptide sequence) with excellent efficiency.