4′-(4-Bromophenyl)-1′-methyldispiro[indan-2,2′-pyrrolidine-3′,2′′-indan]-1,3,1′′-trione

In the title compound, C27H20BrNO3, the pyrrolidine ring adopts a half-chair conformation, while the other five-membered rings adopt flattened envelope conformations with the spiro C atoms as the flap atoms. An intramolecular C—H⋯O hydrogen bond occurs, generating an S(6) ring. In the crystal, molecules are connected via weak C—H⋯O hydrogen bonds, forming chains along the c axis.

In the title compound, C 27 H 20 BrNO 3 , the pyrrolidine ring adopts a half-chair conformation, while the other fivemembered rings adopt flattened envelope conformations with the spiro C atoms as the flap atoms. An intramolecular C-HÁ Á ÁO hydrogen bond occurs, generating an S(6) ring. In the crystal, molecules are connected via weak C-HÁ Á ÁO hydrogen bonds, forming chains along the c axis.

Related literature
For background to tuberculosis, see: Sunduru et al. (2010); Trivedi et al. (2010). For background to anti-tuberculous drugs, see: Moraski et al. (2011); Kumar et al. (2009) ;Maheswari et al. (2010). For puckering parameters, see: Cremer & Pople (1975). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 Table 1 Hydrogen-bond geometry (Å , ). Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 Comment Tuberculosis (TB) is one of the most common chronic infections caused by Mycobacterium tuberculosis and is the world's second common cause of death from infectious diseases after AIDS (Sunduru et al., 2010). Among HIV infected patients, TB is the leading killer epidemic. About 2 million people living with HIV/AIDS die from TB every year (Trivedi et al., 2010). To make things even worse, the emergence of multiple drug resistant TB (MDR-TB), extensively drug resistant TB (XDR-TB) and extremely drug resistant TB (XXDR-TB) are on the rise (Moraski et al., 2011). These lead to the need for development of more potent drugs of new structures and with novel mechanisms of action (Trivedi et al., 2010). In our study, spiro nuclei were used as the core structure due to their potential antimycobacterial properties. Some studies have shown that many of these compounds displayed comparable or even better activities than some of the first-line TB drugs (Kumar et al., 2009;Maheswari et al., 2010).
In the crystal packing, (Fig. 2), the molecules are connected via weak intermolecular C-H···O (Table 1) hydrogen bonds, forming one-dimensional chains along the c-axis.

Refinement
All hydrogen atoms were positioned geometrically [ C-H = 0.95-1.00 Å] and were refined using a riding model, with Fig. 1. The asymmetric unit of the title compound, showing 30% probability displacement ellipsoids.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.