Crystal Structure of 3-(2-Chloro-6-fluorophenyl)-2-(4-methoxyphenyl)-acrylonitrile

Abstract

The use of the nitrile function for the C‐C bond formation reaction occupies an important position in organic chemistry. 1 2,3-Disubstituted acrylonitriles represent an interesting class of biologically active compounds, and are capable of undergoing many useful organic transformations; many have been transformed into bioactive heterocycles. The deprotonation of the α-carbon and alkylation is an especially important reaction. 2 Currently, fluorine containing medicinals are significantly featured in such diverse areas as anti-cancer, antiinflammatory anti-parasitic, central nervous system agents, anti-biotics, general anesthetics, as well as in cardiac therapy. This prompted us to synthesize an acrylonitrile containing a fluorine atom, which serves as a new dipolarophile used in the construction of bioactive heterocycles. We found from the literature that the olefinic bond had a Z-configuration irrespective of the size of the substituents on the heterocyclic rings. In order to confirm the olefinic bond geometry connected to (4-methoxyphenyl)acetonitrile and 2-chloro-6-fluorobenzaldehyde rings and to obtain the structural conformation details of the molecule, the title compound was synthesized. Its crystal structure is reported here. To a well-stirred suspension of 2-chloro-6-fluorobenz aldehyde (1.07 g, 6.79 mmol) in a 5% NaOH (10 ml) solution, (4-methoxyphenyl)acetonitrile (1 g, 6.79 mmol) was added along with a catalytic amount of tert-butylammonium bromide. The mixture was stirred at room temperature for 45 min, saturated with sodium chloride solution and extracted with diethyl ether (3 × 15 ml). The combined organic layer was dried over anhydrous sodium sulfate and evaporated under a vacuum to obtain the crude mass, which upon recrystallization with methanol gave a colorless crystalline solid. Melting point: 102˚C. Single crystals suitable for a structural analysis were obtained by a slow evaporation technique using methanol as a solvent. A schematic diagram of the molecule is shown in Fig. 1. A single crystal of the title compound with dimensions 0.3 × 0.27 × 0.25 mm was chosen for an X-ray diffraction study. The data were collected on a DIPLabo Image Plate system equipped with a normal focus, 3 kW sealed X-ray source (graphite monochromated Mo Kα). The crystal-to-detector distance was fixed at 120 mm with a detector area of 441 × 240 mm 2 . Thirty six frames of data were collected at room temperature by the oscillation method. Each exposure of the image plate was set to a period of 400 s. Successive frames were scanned in steps of 5˚ per min with an oscillation range of 5˚. Image processing and data reduction were done using Denzo. 3 All of the frames x291