Crystal structure of 1′,1′′-dimethyl-4′-(4-cholorophenyl)dispiro[11H-indeno[1,2-b]quinoxaline-11,2′-pyrrolidine-3′,3′′-piperidin]-4′′-one

In the title compound, C30H27ClN4O, the central pyrrolidine ring adopts an envelope conformation with the methylene C atom being the flap. The quinoxaline and indane rings are each essentially planar, with r.m.s. deviations of 0.027 (1) and 0.0417 (1) Å, respectively. The pyrrolidine ring forms dihedral angles of 88.25 (1) and 83.76 (1)° with the quinoxaline and indane rings, respectively. A weak intramolecular C—H⋯N interaction is observed. In the crystal, C—H⋯π interactions lead to supramolecular chains along [101] that assemble in the ac plane. Connections along the b axis are of the type Cl⋯Cl [3.6538 (16) Å].

Cg1 is the centroid of the C14-C19 ring.  et al., 2002), and dyes (Dailey et al., 2001). Quinoxaline derivatives were found to exhibit anti-microbial (Kleim et al. 1995), antitumor (Abasolo et al., 1987, and anti-tuberculous activity (Rodrigo et al., 2002). Our interest in preparing pharmacologically active quinoxaline derivatives led us to the title compound, and we have undertaken X-ray crystal structure determination in order to establish its conformation.

S2. Structural commentary
In the title compound ( Fig. 1), C 30 H 27 ClN 4 O, the central pyrrolidine ring is an envelope on C2 with the asymmetry parameters ΔC s (C2) = 7.6 (2) Å and puckering parameters q 2 = 0.433 (2)  ). This may be due to the the steric interactions of the bulky substituents at atoms C4 and C5 of the pyrrolidine ring.
A weak intra-molecular C-H···N interaction is observed (Table 1). In the crystal, C-H···π interactions lead to supramolecular chains along [101] that assemble in the ac plane. Connections along the b axis are of the type Cl···Cl (3.6538 (16) Å).
Suitable crystals for the single crystal-X-ray studies were obtained by recrystalizing the product from methanol. Yield: 42%, Melting point: 450-452 K.

S4. Refinement
All the H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.98 Å, and with U iso = 1.2U eq (C) for CH 2 and CH groups, and U iso = 1.5U eq (C) for CH 3 groups. The (-1 1 1), (1 1 0) reflections were affected by the beam-stop and were removed from the final refinement. The best crystal investigated was still of poor quality and very weakly diffracting, with no usable data obtanied above θ = 23.8°. Nonetheless, the structure was solved readily and refined to give acceptable uncertainties on the metrical data.