Structure of kidamycin : x-ray analysis of isokidamycin derivatives

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

“…Treatment of kidamycin (1) with p-toluenesulfonic acid (see Scheme 6) provokes this epimerization at C(6") leading to isokidamycin (26) (28). In this compound, ring F now adopts a chair conformation with the aryl substituent oriented equatorially (29). The X-ray crystallographic studies mentioned, further yielded information about the orientation of the C(2) side chain with respect to the pyrone ring A, i.e.…”

“…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.…”

“…The compound proved to be rather interesting in connection with the structure determination of kidamycin (29), the conformational analysis of ring F (86), and some first experiments towards an understanding of the structure-activity relationship with the pluramycins (24).…”

“…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).…”

The structures of kidamycin derivatives: triacetylmethoxykidamycin bis(trimethylammonium) iodide and isokidamycin bis(m-bromobenzoate)

“…At the final stage of the analysis, a disorder of the m-bromobenzoyl group was noticed, as shown in Figs. 1 and 2 of a previous paper (Furukawa & Iitaka, 1974). The site-occupancy factors for the a and b sites in molecule A were estimated on the electron density map to be 0.66 for a and 0.34 for b and these values were fixed in the refinement.…”