Total synthesis of Piperazic acid-containing natural products: Piperazimycin A and Chloptosin Liu Bin Alexander J. Oelke, Steven V. Ley, etc. Angew. Chem. Int. Ed. 2010, 49, 6139 Shun-Ming Yu, Zhu-Jun Yao. etc. Org. Lett. 2010, 12, Theodore M. Kamenecka, Samuel J. Danishefsky. Angew. Chem. Int. Ed. 1998, 37, 2993 Wenhua Li, Dawei Ma. etc. Angew. Chem. Int. Ed. 2009, 48, 8891 Key challenges: 1) formation of the piperazic acid piperazic acid dipeptide moiety 2) formation of the macrocycle by macrolactonisation Generation of acyl azides for peptide coupling 2. 1. Feature: enantioselective preparation of the piperazic acid Generation of acyl chloride for peptide coupling