The Crystal Structure of Ascochlorin p-Bromobenzenesulfonate

Abstract

Abstract The structure of ascochlorin, C23H29O4Cl, has been determined by the three-dimensional X-ray crystal structure analysis of ascochlorin p-bromobenzenesulfonate. The crystal is orthorhombic, space group P212123, with four molecules in a unit cell of dimensions, a=13.86, b=30.04, and c=6.82 Å. The structure was solved by the heavy atom method and refined by the method of block-matrix least-squares. The final R value was 0.102 for 1627 independent reflexions. Ascochlorin consists of (3-chloro) orcylic aldehyde and (2,3,4-trimethyl) cyclohexanone moieties which are connected with each other through a zigzag chain of trans-(3-methyl)penta(2,4)diene. The cyclohexanone ring takes a typical chair form, and the intramolecular hydrogen bond exists in the orcylic aldehyde residue. The absolute configuration was determined by the anomalous dispersion method.