Crystallographic studies of an anthraquinone derivative obtained from kidamycin

The Antibiotics of the Pluramycin Group (4 H-Anthra [1,2-b] pyran Antibiotics)

“…8) (30), of the isokidamycin derivatives (28) and (29) (29), and of hedamycin (17) (see Fig. 9) (105) -besides confirming the constitutions and configurations -yielded information about the conformations of these compounds in the crystalline state.…”

“…It is one of the best investigated puramycins and the first compound of this family of antibiotics whose structure was fully elucidated. The constitution and configuration were determined from chemical and NMR spectroscopical investigations (28) in conjunction with X-ray analyses of the bis(m-bromobenzoyl) and bis(m-iodobenzoyl) derivatives (28) and (29) of isokidamycin (26) (29) (see Scheme 1) as well as of the rather peculiar kidamycin derivative (30), where C(12) is in fact the acetylated methyl hemiketal of the parent quinone (30). The fact that the structure of kidamycin had been determined unambig- Kidamycin (1) is the only pluramycin antibiotic where an effort was made to reduce its toxicity and thus get a better therapeutic index by derivatization.…”

“…Quaternization of the dimethylamino groups was also undertaken: When triacetylkidamycin (5) was dissolved in methyl iodide, crystals of the bis methiodide (44) separated from the solution overnight (28). The most spectacular derivative (30) was, however, obtained unexpectedly when this bis-methiodide was recrystallized from methanol/ethyl acetate (30). The compound (30) is formally derived from (44) by the addition of methanol to the quinone and subsequent acetyl migration (see Scheme 8).…”

“…The assumption that all other pluramycins probably also share this same absolute configuration seems reasonable. X-ray crystallography (using the anomalous dispersion procedure) was used to determine the absolute configuration of the quaternized triacetylkidamycin methanolysis product (30) (30) and of the isokidamycin derivatives (28) and (29) (29). The absolute configuration of hedamycin (17) was related to that of the kidamycin derivatives by comaprison of the CD curves of hedamycin and kidamycin (105).…”

“…Thus the conformation found is characteristic for this specific compound but not necessarily also for the parent kidamycin (1). Ever since the publication of the paper by FURUKAWA et al (30), formulae of pluramycin antibiotics were drawn with ring F in a boat confor· mation. The X-ray structure determination ofhedamycin (17), however, was carried out with the underivatized antibiotic using direct methods.…”