2-(2-Chlorophenyl)-3-methyl-5,6-diphenyl-2,3-dihydropyrazine

In the title molecule, C23H19ClN2, the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The benzene ring at position 2 makes dihedral angles of 77.88 (12) and 76.31 (12)° with the phenyl rings at positions 5 and 6, respectively. The dihedral angle between the phenyl rings at positions 5 and 6 is 70.05 (10)°. The Cl atom is disordered over two positions with occupancy factors of 0.946 (5) and 0.054 (5). In the crystal, C—H⋯π interactions are found.

In the title molecule, C 23 H 19 ClN 2 , the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The benzene ring at position 2 makes dihedral angles of 77.88 (12) and 76.31 (12) with the phenyl rings at positions 5 and 6, respectively. The dihedral angle between the phenyl rings at positions 5 and 6 is 70.05 (10) . The Cl atom is disordered over two positions with occupancy factors of 0.946 (5) and 0.054 (5). In the crystal, C-HÁ Á Á interactions are found.

Related literature
For the biological properties of heterocyclic ring systems having a dihydropyrazine nucleus, see: Sondhi et al. (2005). For the use of dihydropyrazines, with reference to DNA breakage activity, see: Takechi et al. (2011). For the inhibition of the growth of Escherichia coli, see: Takeda et al. (2005). For a closely related crystal structure, see: Anuradha et al. (2009 Table 1 Hydrogen-bond geometry (Å , ).

Comment
Heterocyclic ring systems having the dihydropyrazine nucleus have aroused great interest in the past and recent years due to their wide variety of biological properties (Sondhi et al., 2005). Dihydropyrazines are used to break DNA strands and inhibit bacterial growth (Takechi et al., 2011). In addition, these compounds have inhibited the growth of Escherichia coli (Takeda et al., 2005). Anuradha et al. (2009) have reported the crystal structure of 2-methyl-3,5,6-triphenyl-2,3-dihydropyrazine, in which the heterocyclic ring adopts a screw-boat conformation.

Experimental
To a homogeneous solution of benzil (1.05 g, 0.005 mol) and 1-methyl-2-(2'-chlorophenyl)-ethanediamine dihydrochloride (1.29 g, 0.005 mol) in ethanol (20 ml), sodium acetate trihydrate (2.04 g, 0.015 mol) was added. The precipitated sodium chloride was filtered off and the filtrate was refluxed for 2 h. On completion of the reaction, as indicated by TLC, the reaction mixture was poured into crushed ice and the resulting solid was filtered and purified by column chromatography on silica gel. Elution with benzene-petroleum ether (3:2 v/v) at 333-353 K gave the pure product (1.68 g) in 76% yield. Crystals suitable for X-ray diffraction studies were obtained by recrystallization of the pure product from ethyl acetate.  Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 25% probability level. H atoms are shown as small spheres of arbitrary radius. as those based on F, and R-factors based on ALL data will be even larger.

2-
To allow for a stable and meaningful refinement of the Cl atoms, the C-Cl bonding distances were restrained to be the same