2-Cyano-3-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)prop-2-enoic acid dimethyl sulfoxide monosolvate

In dimethyl sulfoxide solvated 9-(2-carboxy-2-cyanovinyl)julolidine, C16H16N2O2·C2H6OS, the essentially planar –CH=(CN)–CO2H substituent (r.m.s. deviation = 0.014 Å) is almost coplanar with respect to the benzene ring, the dihedral angle between the two planes being 0.48 (2)°. The conformations of the fused, non-aromatic rings were found to be half-chair. In the crystal, the acid molecule forms a hydrogen bond to the O atom of the solvent molecule. The acid molecule is disordered over two positions with respect to the methylene C atoms in a 1:1 ratio. The crystal studied was found to be a racemic twin.

In dimethyl sulfoxide solvated 9-(2-carboxy-2-cyanovinyl)julolidine, C 16 H 16 N 2 O 2 ÁC 2 H 6 OS, the essentially planar -CH (CN)-CO 2 H substituent (r.m.s. deviation = 0.014 Å ) is almost coplanar with respect to the benzene ring, the dihedral angle between the two planes being 0.48 (2) . The conformations of the fused, non-aromatic rings were found to be halfchair. In the crystal, the acid molecule forms a hydrogen bond to the O atom of the solvent molecule. The acid molecule is disordered over two positions with respect to the methylene C atoms in a 1:1 ratio. The crystal studied was found to be a racemic twin.

Experimental
CCVJ was synthesized by reaction of 9-formyljulolidine and cyanoacetic acid as described by Rumble et al. (2012) and purified by silica gel flash chromatography. Orange colored crystals were obtained by slow evaporation of its solution in toluene with a small quantity of DMSO added to increase the solubility, at room temperature.

Refinement
Hydrogen atoms were placed in calculated positions with C-H 0.93 and 0.97 Å in a riding-model approximation. The acid hydrogen was located in a difference Fourier map and was freely refined.
The acid is disordered over two positions in respect of the five methylene carbons. The occupancy could not be refined so that the disorder was assumed to be a 1:1 type of disorder. Pairs of 1,2-related C-C distances were restrained to within 0.01 Å of each other, and the temperature factors of the primed atoms were set to those of the unprimed ones.
Additionally, the anisotropic temperature factors were tightly restrained to be nearly isotropic.
The Flack parameter, refined on 1096 Friedel pairs, was 0.5, which implied that the crystal studied is a racemic twin that crystallizes in a polar space group. The racemic nature also supported the 1:1 type of disorder. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: