ALDECALMYCIN, A NEW ANTIMICROBIAL ANTIBIOTIC FROM STREPTOMYCES .2. STRUCTURE ELUCIDATION BY NMR-STUDIES

A new antibiotic, aldecalmycin (1) was isolated from the culture broth of Streptomyces sp. MJ147-72F6. The H-1 and C-13 NMR spectra of 1 wer e complicated due to the presence of a beta-ketoaldehyde moiety. There fore, 1 was converted into an ethylene ketal derivative (2) and into a dihydroaldecalmycin (3). These derivatives gave assignable NMR spectr a. The planar structure was elucidated by using H-1-H-1 COSY, 2D-HOHAH A, H-1-C-13 COSY and HMBC spectra of 2. The conformation of the decali n ring was elucidated by using 1D-HOHAHA, NOE difference and NOESY spe ctra of 3. The geometry of double bond in the side chain was determine d by NOE difference and NOESY spectra of 3.