Relative and Absolute Configuration of Filipin III

Abstract

NMR spectroscopy, Mosher's ester analysis, degradation, and synthesis of the C26–C27 fragment unraveled the relative and absolute configuration of the natural antibiotic, filipin III. The relative configurations for the nine stereogenic centers in the top half of the formula for filipin shown on the right were determined from just three acetonide derivatives that arose in a two-step protection sequence.