Synthesis and NMR Studies of Cyclopeptides Containing a Sugar Amino Acid

Cyclopeptides containing Glucuronic acid methylamine (Gum) alternating with Gly, l-Ala, d-Ala, l-Phe, d-Phe, l-Lys, or d-Lys were synthesized by a combination of solid-phase synthesis and solution chemistry. A more effective pathway to synthesize the sugar amino acid Gum in higher yields and in a shorter period of time was developed. Gum is employed in the benzylated and deprotected form. The cyclopeptides were characterized by NMR and the structure of one deprotected cyclic peptide solved.