Total Synthesis of Azumamide E and Sugar Amino Acid-Containing Analogue

An efficient and practical total synthesis of marine cyclic tetrapeptide, natural product azumamide E (1) is achieved via high-yielding reactions. The strategy also allowed us to synthesize the azumamide E-SAA (sugar amino acid) analogue (2), whose solution-phase NMR and biological activity studies were also carried out.