N-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-N-propionylpropionamide

In the title molecule, C16H14ClNO4, the four essentially planar atoms of the imide group [r.m.s. deviation = 0.0286 (11) Å] form a dihedral angle of 77.36 (13)° with the naphthoquinone group [maximun deviation = 0.111 (2) Å for the carbonyl O atom in the naphthalene 1-position] and the two imide carbonyl groups are oriented anti with respect to each other. In the crystal, molecules are connected by weak C—H⋯O hydrogen bonds, as well as π–π stacking interactions [centroid–centroid distance = 3.888 (3) Å], forming a three-dimensional network.

In the title molecule, C 16 H 14 ClNO 4 , the four essentially planar atoms of the imide group [r.m.s. deviation = 0.0286 (11) Å ] form a dihedral angle of 77.36 (13) with the naphthoquinone group [maximun deviation = 0.111 (2) Å for the carbonyl O atom in the naphthalene 1-position] and the two imide carbonyl groups are oriented anti with respect to each other. In the crystal, molecules are connected by weak C-HÁ Á ÁO hydrogen bonds, as well asstacking interactions [centroid-centroid distance = 3.888 (3) Å ], forming a threedimensional network.

Comment
Our group are involved in the synthesis and biological evaluation of some imido-substituted 1,4-naphthoquinone derivatives (Bakare et al., 2003;Berhe et al., 2008;Brandy et al., 2013), and have previously reported that 2-chloro-3dipropionylamino-1,4-naphthoquinone and some of its analogs possess inhibitory activities against certain protein kinases (Bakare et al., 2003). This class of compounds have also been shown to possess anticancer (Bakare et al., 2003;Berhe et al., 2008) and anti-trypanosomal activities (Khraiwesh, et al., 2012). As part of our studies  on the synthesis, properties, and structural characterization of this class of compounds, we herein present, the crystal structure of the title compound.

Experimental
The title compound was synthesized by refluxing 2-amino-3-chloro-1,4-naphthoquinone in propionyl chloride as previously reported (Bakare et al. (2003)). The crude compound thus obtained was crystallized from ethanol to obtain yellow crystals suitable for X-ray studies.

Refinement
H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C-H distances of 0.93 and 0.97 Å U iso (H) = 1.2U eq (C) and 0.96 Å for CH 3 [U iso (H) = 1.5U eq (C)].

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  The molecular structure of the title compound with displacement parameters shown at the 30% probability level.  The crystal packing viewed along the a axis showing the weak C-H···O hydrogen bonds (as dashed lines) as well as the π-π stacking along the b axis.  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.