Crystal structure of the thalidomide analog (3aR*,7aS*)-2-(2,6-dioxopiperidin-3-yl)hexahydro-1H-isoindole-1,3(2H)-dione

Abstract

The title compound, C13H16N2O4, crystallizes in the monoclinic centrosymmetric space group, P21/c, with four molecules in the asymmetric unit, thus there is no crystallographically imposed symmetry and it is a racemic mixture. The structure consists of a six-membered unsaturated ring bound to a five-membered pyrrolidine-2,5-dione ring N-bound to a six-membered piperidine-2,6-dione ring and thus has the same basic skeleton as thalidomide, except for the six-membered unsaturated ring substituted for the aromatic ring. In the crystal, the molecules are linked into inversion dimers by R22(8) hydrogen bonding involving the N—H group. In addition, there are bifurcated C—H...O interactions involving one of the O atoms on the pyrrolidine-2,5-dione with graph-set notation R12(5). These interactions along with C—H...O interactions involving one of the O atoms on the piperidine-2,6-dione ring link the molecules into a complex three-dimensional array. There is pseudomerohedral twinning present which results from a 180° rotation about the [100] reciprocal lattice direction and with a twin law of 1 0 0 0 \overline{1} 0 0 0 \overline{1} [BASF 0.044 (1)].

Keywords

• crystal structure
• thalidomide analogs
• pseudomerohedral twinning