Complete Stereochemical Assignment of Campechic Acids A and B

Campechic acids A and B are anti-invasive polyketide antibiotics isolated from Streptomyces sp. CHI93 strain. Herein we describe stereoselective synthesis of the C-16-C-30 fragment of campechic acids A and B via a biosynthesis-inspired epoxide-opening cascade and its NMR spectroscopic comparison with the authentic degradation product, resulting in configurational assignment of the C-21, C-24, C-25, and C-28 stereogenic centers and reassignment of the C-18 stereogenic center.