The structure of acetomycin. Spectroscopic characterization and X-ray analysis of a bromo derivative

Acetomycin (1a), known since 1958, has been further characterized by NMR and CD spectra. The 3-acetyl side chain of 1a is reduced selectively by sodium cyanoborohydride yielding the diastereomeric alcohols 2a and 3a, which were esterified to the crystalline bromoacetates 2c and 3c. The structure and absolute configuration of 3c was determined by X-ray analysis. From these data the absolute configuration of 1a followed as 3S, 4S, 5R.