Date Published: May 01, 2012
Publisher: International Union of Crystallography
Author(s): F. L. Oliveira, K. R. L. Freire, R. Aparicio, F. Coelho.
The crystal structure of the title compound, C14H14N2O5, contains two distinct conformers in the asymmetric unit. The compound has three defined stereocenters, two of them contiguous, and a C=C double bond with an E conformation. The stereocenters exhibit the same chirality in both conformers, with significant differences in the conformation of the five-membered rings of the pyrrolizine unit (both either in a twist or in an envelope form) and in the dihedral angles between the corresponding mean planes and the benzene rings. A prominent feature is a change from almost coplanar rings in one conformer to a new conformation in the second conformer, in which the mean plane of a five-membered ring is almost perpendicular to the benzene ring, with a dihedral angle 87.19 (8)°; the corresponding angle in the first conformer is 14.02 (10)°. In the crystal, molecules are linked by O—H⋯O and C—H⋯O hydrogen bonds. Crystallographic data were essential to confirm the configuration of the double bond, which was unclear from the available two-dimensional NMR data. In addition, reliable Flack and Hooft parameters were obtained, allowing for the correct absolute structure to be determined.
For the preparation of the title compound, see: Freire et al. (2011 ▶). For the use of this type of compound as LFA-1 (Lymphocyte Function-Associated Antigen-1) inhibitors, see: Baumann (2007 ▶). For related structures, see: Oliveira et al. (2012a ▶,b ▶).