A Chiron Approach to the Total Synthesis of (-)-Juglomycin A, (+)-Kalafungin, (+)-Frenolicin B, and (+)-Deoxyfrenolicin

A general, efficient, and common strategy for the synthesis of (-)-juglomycin A, (+)-kalafungin, (+)-frenolicin B, and (+)-deoxyfrenolicin is reported here. The strategy involves the synthesis of a key building block alkyne from a cheap chiral pool material, D-glucono-delta-lactone, Dotz benzannulation, oxa-Pictet-Spengler reaction, and H2SO4-mediated epimerization.