The Structure of the Antibiotic Hedamycin. V. Crystal structure and absolute configuration

Abstract
The crystal structure of the antibiotic hedamycin (1) has been solved by direct method and refined by least squares techniques to R = 0.091 for 2289 of 2643 independent reflexions. Crystals of C41H50N2O11 are orthorhombic, space group P212121 with lattice parameters a = 24.239 (12), b = 21.440 (10), c = 7.369 (4) Å, Z = 4. The structural features of hedamycin derived earlier by chemical and spectroscopical means are confirmed. Optical rotation and circular dichroism indicate that hedamycin (1) has the absolute configuration of the related antibiotic kidamycin (3). The conformation of ring F is a chair form with the aryl substituent almost axial. The bioxirane part of the antibiotic is in a synclinal conformation.