Methyl 2-amino-4-(3-chloropropoxy)-5-methoxybenzoate

The asymmetric unit of the title compound, C12H16ClNO4, contains two crystallographically independent molecules. The benzene rings of the two independent molecules are oriented at a dihedral angle of 88.50 (3)°. Intramolecular N—H⋯O hydrogen bonds involving the methoxybenzoate carbonyl group in each molecule result in the formation of two planar, six-membered rings, oriented at dihedral angles of 1.39 (3) and 0.68 (3)° with respect to the adjacent benzene rings. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules into chains along the a axis.

The asymmetric unit of the title compound, C 12 H 16 ClNO 4 , contains two crystallographically independent molecules. The benzene rings of the two independent molecules are oriented at a dihedral angle of 88.50 (3) . Intramolecular N-HÁ Á ÁO hydrogen bonds involving the methoxybenzoate carbonyl group in each molecule result in the formation of two planar, six-membered rings, oriented at dihedral angles of 1.39 (3) and 0.68 (3) with respect to the adjacent benzene rings. In the crystal structure, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into chains along the a axis.

Comment
As part of our ongoing studies on quinazoline derivatives (Knesl et al., 2006), we report herein the crystal structure of the title compound.
The asymmetric unit of the title compound contains two crystallographically independent molecules (Fig. 1), in which the bond lengths (Allen et al., 1987) and angles are within normal ranges. Rings A (C4-C9) and A' (C16-C21) are, of course, planar and they are oriented at a dihedral angle of A/A' = 88.50 (3)°. Intramolecular N-H···O hydrogen bonds (Table 1)  In the crystal structure, intra-and intermolecular N-H···O hydrogen bonds (Table 1) link the molecules into chains along the a axis (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title compound, a suspension of methyl 4-(3-chloro-propoxy)-5-methoxy-2-nitrobenzoate (0.016 mol) in HCl (100 ml) was heated at 323-333 K for 5 min, and then a solution of tin(II) chloride (16.0 g, 0.1 mol) in HCl (20 ml) was added dropwise. The reaction mixture was heated at 363-373 K for 45 min. The solid formed was collected and dissolved in water (300 ml). A solution of sodium hydroxide (2N) was added to obtain pH = 8-9. The aqueous solution was then extracted with ethyl acetate (3 × 100 ml). The combined organic layers were dried over magnesium sulfate and concentrated in vacuo to give the title compound (yield; 2.3 g, 51.1%, m.p. 377 K). Crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH 2 ) and C-H = 0.93, 0.97 and 0.96 Å for aromatic, methylene and methyl H, respectively, and constrained to ride on their parent atoms, with U iso (H) = xU eq (C,N), where x = 1.5 for methyl H and x = 1.2 for all other H atoms.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq