Total Synthesis of Nannocystin Ax
Total synthesis of nannocystin Ax, a natural depsipeptide isolated from myxobacteria recently, has been accomplished concisely. By following a convergent strategy, the target molecule was assembled from three fragments. Each fragment can be synthesized expeditiously from readily achievable compounds. The key elements in this total synthesis features Kobayashi’s remote asymmetric induction with vinylketene silyl N, O-acetal, Roush’s asymmetric crotylboration of aldehyde, Mitsunobu’s esterification and macrocyclization via Stille cross-coupling.