Crystal and molecular structure of 5-diacetylamino-3,4-diphenylisoxazole

Abstract

The structure of (IV) the acetylation product of 5-amino-3,4-diphenylisoxazole has been investigated by spectroscopic methods and determined from three-dimensional X-ray diffraction data. Crystals are orthorhombic, space group P2₁2₁2₁ with Z= 4 in a unit cell of dimensions: a= 9·216(4), b= 9·324(5), and c= 19·043(8)Å. The crystal structure has been solved by direct methods and refined by block-diagonal least-squares to R 0·063 (1282 independent reflections). The bond lengths of the isoxazole and of the phenyl rings are as expected. The two bonds linking the phenyl rings to the central isoxazole ring, however, are significantly shorter (1·449 and 1·450 Å) than expected for the C(sp²)–C(sp²) bond (1·482 Å). The planes of the phenyl rings and of the two acetyl groups are twisted differently about the bonds linking them to the isoxazole ring.