Structure of herbimycin A new ansamycin antibiotic

✍ Scribed by S. Ōmura; A. Nakagawa; N. Sadakane

• Publisher: Elsevier Science
• Year: 1979
• Tongue: French
• Weight: 245 KB
• Volume: 20
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)86578-3

✦ Synopsis

Herbimycin is a new potent herbicidal antibiotic isolated from the cultured filtr te of wtr?i'r anwosynthetic means usin:)&-labeled precursors. re to ces (Sm.) h rosco icus AM-3672 We assign st cture 1 to herblmycin based on ' H-and The molecular formula, C30H42N209 for herbimycin (1) was established from the elemental analysis and high-resolution mass (M+, m/e 574) in the early report 1) . The UV spectrum (MeOH) of 1 shows characteristic absorption maxima at 270 nm (E 20090) and 392.5 nm (E 1650), indicating the presence of benzoquinone nucleus 2) as a chromophore. The 'H-and 13C-nmr spectra of 1 indicate that1 is structurally similar to geldanamycin (Z), ansamycin antibiotic, the structure of which has been determined by Rinehart et al. 3) The presence of the following functional groups in 1 was deduced from the 'H-and 13 C-nmr (CDC13) and ir (CHC13) spectra: OCONH2 [S 4.87 (broad s), exchange with D20, 1730 cm-'], CONH [S 8.78 (s), exchange with D20, 1655 cm-'], four OCH3 (6 56.0, 57.6, 58.4 and 59.8), benzoquinone carbonyls (6 187.7 and 183.9, 1690 cm-'), two K-methyl protons (6 0.82 and 1.09), two methyl protons (6 1.65 and 2.01) attached to double bond, a methylene carbon (6 34.0), a conjugated diene protons [S 6.95 (broad d), 6.48 (t) and 5.84 (q)] and an isolated double bond proton [6 5.50 (broad d)]. The substitution pattern of . benzoquinone nucleus was deduced from the 'H-nmr spectral evidence; two protons observed at