3-Butyl-2-propylamino-1-benzothieno[3,2-d]pyrimidin-4(3H)-one

In the title compound, C17H21N3OS, the propyl and butyl groups are disordered over two positions; site occupation factors are 0.304 (10) and 0.696 (10). The three fused rings are coplanar. In the crystal structure, intermolecular N—H⋯O and C—H⋯O hydrogen bonds link the molecules. Further stability is provided by offset π–π stacking interactions. Adjacent thienophene–pyrimidine and pyrimidine–benzene rings have centroid–centroid distances of 3.96 (1) and 3.55 (2) Å, respectively.

In the title compound, C 17 H 21 N 3 OS, the propyl and butyl groups are disordered over two positions; site occupation factors are 0.304 (10) and 0.696 (10). The three fused rings are coplanar. In the crystal structure, intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the molecules. Further stability is provided by offsetstacking interactions. Adjacent thienophene-pyrimidine and pyrimidine-benzene rings have centroid-centroid distances of 3.96 (1) and 3.55 (2) Å , respectively.

3-Butyl
Thienopyrimidine derivatives are of interest as possible antiviral agents, and because of their other biological properties, including antibacterial, antifungal, antiallergic and anti inflammatory activities (Chambhare et al., 2003). We have recently focused on the synthesis of the fused heterocyclic systems containing thienopyrimidine via aza-Wittig reactions at room temperature (Ding et al., 2004). We report herein the structure of one such thienopyrimidine derivative, the title compound, (I).
In the molecule of (I), (Fig. 1) the bond lengths and angles are generally within normal ranges (Allen et al., 1987). When the crystal structure was solved, propyl and butyl groups were found to be disordered.
In the crystal structure, intermolecular N-H···O and C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. Further stability is provided by offset π-π stacking interactions (Janiak, 2000). The adjacent B, C and A, C rings have centroid-centroid distances of 3.96 (1) %A and 3.55 (2) %A, respectively, [symmetry code: −x, −y, 2 − z].

Experimental
The title compound was synthesized according to a literature method (Ding et al., 2004). The product was recrystallized from ethanol/dichloromethane (1:2 v/v) at room temperature to give crystals suitable for single-crystal X-ray analysis.

Special details
Geometry. All e.s. 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 > 2sigma(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.