7′-Methyl-5′-oxo-2′,3′-dihydrospiro[1,3-dioxolane-2,1′(5′H)-indolizine]-6′-carbonitrile

In the title compound, C12H12N2O3, the five-membered ring attached to the aromatic ring adopts an envelope conformation with a C atom in the flap position. The spiro-linked five-membered ring adopts a twisted conformation. In the crystal, C—H⋯O hydrogen bonds link the molecules into C(5) chains propagating in [001].

In the title compound, C 12 H 12 N 2 O 3 , the five-membered ring attached to the aromatic ring adopts an envelope conformation with a C atom in the flap position. The spiro-linked fivemembered ring adopts a twisted conformation. In the crystal, C-HÁ Á ÁO hydrogen bonds link the molecules into C(5) chains propagating in [001].
(4H,12H)-dione, is a pentacyclic alkaloid. Two CPT analogues, topotecan and irinotecan, have been approved and are used in cancer chemotherapy (Takimoto & Calvo, 2008). As part of our studies into the synthesis of Camptothecin, the title compound, (I), was synthesized (Wani et al., 1980). We report herein the crystal structure of the title compound.
In the molecule of the title compound, (Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, C-H···O hydrogen bonds link the molecules (Fig. 2), based on the geometrically positioned H5B atom, in which they may be effective in the stabilization of the structure.

Experimental
A mixture of 1,2,3,5-tetrahydro-7-methyl-1,5-dioxo-6-Indolizinecarbonitrile, (13.0 g,0.069 mol), ethylene glycol (210 ml), and p-toluenesulfonic acid (1.1 g) in toluene (1.0 L) was refluxed using a Dean-Stark trap for 5 h. The toluene layer was decanted and another liter of toluene was added. The reaction mixture was refluxed for an additional 5 h and the toluene layer decanted as before. After repeating this procedure two more times, the toluene layers were combined, washed with brine, dried, and evaporated to yield the crude product, which was crystallized from MeOH to give the title compound (93%) (Wani et al., 1980). Colourless blocks of (I) were obtained by slow evaporation of an MeOH solution.

Refinement
Anomalous dispersion was negligible and Friedel pairs were merged before refinement. H atoms were positioned geometrically with C-H = 0.93, 0.98 and 0.97 Å for aromatic, methine and methylene H atoms, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2 (or 1.5 for methyl groups) times U eq (C). Fig. 1. The molecular structure of (I) with displacement ellipsoids are drawn at 30% probability levels.