8-Bromo-3-(cyclopropanylcarbonyl)-5-methylindolizine-1-carbonitrile

The asymmetric unit of the title compound, C14H11BrN2O, contains three independent molecules with very similar geometries. The dihedral angles between the side chain of the cyclopropyl plane and the five-membered ring to which it is attached are 55.0 (2), 58.1 (2) and 60.2 (3)° for the three molecules. Each molecule forms an intramolecular C—H⋯O hydrogen bond.

We greatly appreciate the financial support of the Foundation of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (AE201017) and the Scientific Project of Yancheng Institute of Technology (XKY2011003).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2561).
supplementary materials . E68, o1897 [doi:10.1107/S1600536812023161] 8-Bromo-3-(cyclopropanylcarbonyl)-5-methylindolizine-1-carbonitrile Dahe Fan, Fan Tang and Wei Wang Comment Indolizines have been drawing greatly research interest owing to their special electronic structures high fluorescence efficiency (Shen et al., 2007), wide range of biological activity (Sippl, 2002;Wu et al., 2011) and the fact that their partially hydrogenated frameworks have been found in several natural products (Sriram et al., 2005). Meanwhile, the cyclopropane is a noteworthy structural motif because of its own biological activity and its effect to modify the bioactivity of the parent compounds (Shen et al., 2010). We report here the synthesis and crystal structure of the title indolizine compound which is containing cyclopropylcarbonyl group.
The molecular structure of the title compound is shown in Fig. 1. In the title compound, The distance of C-Br bond for these three molecules is 1.883 (3), 1.879 (3), 1.887 (3) Å respectively, similar to the value of 1.882 (3) Å found in the previously reported structure [Wu et al. (2011)]. The values of the geometric parameters for the others in the structure are normal (Allen et al., 1987). the indolizine plane is slightly twisted, with maximum deviations of 5.979 (7), 7.111 (8), and 7.0657 Å from the mean plane. The dihedral angle between the side chain of the cyclpropyl plane and the five-membered ring to which it is attached is 54.98 (20)°, 58.10 (21)° and 60.18 (30)° for the three molecules in the asymmetric unit.
Each molecule forms an intramolecular C-H.. O hydrogen bond.

Refinement
The H atoms were fixed geometrically and were treated as riding on their parent C atoms, with C-H distances in the range of 0.93-0.97 Å, and with U iso (H) = 1.2U eq (parent atom), or U iso (H) = 1.5U eq (C methyl ).  The molecular structure of the title compound, with 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds.

8-Bromo-3-(cyclopropanylcarbonyl)-5-methylindolizine-1-carbonitrile
Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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 > σ(F 2 ) is used only for calculating R-factors(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.