Methyl 4-amino-3-methylbenzoate

In the molecule of the title compound, C9H11NO2, the methyl C and amino N atoms bonded to the benzene ring lie in the ring plane. Intramolecular C—H⋯O hydrogen bonding results in the formation of a five-membered planar ring, which is oriented at a dihedral angle of 2.73 (3)° with respect to the benzene ring, so they are nearly coplanar. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules into chains elongated along the c axis and stacked along the b axis.

In the molecule of the title compound, C 9 H 11 NO 2 , the methyl C and amino N atoms bonded to the benzene ring lie in the ring plane. Intramolecular C-HÁ Á ÁO hydrogen bonding results in the formation of a five-membered planar ring, which is oriented at a dihedral angle of 2.73 (3) with respect to the benzene ring, so they are nearly coplanar. In the crystal structure, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into chains elongated along the c axis and stacked along the b axis.

Comment
Methyl 3-methyl-4-aminobenzoate is important as an intermedicine to prepare telmisartan, an angiotensin II receptor blocker, on the development of obesity and related metabolic disorders in diet-induced obese mice (Ries et al., 1993). Telmisartan can be used as a therapeutic tool for metabolic syndrome, including visceral obesity (Engeli et al., 2000;Kintscher et al., 2004;Goossens et al., 2003;Kurtz et al., 2004). As part of our studies in this area, we report herein the synthesis and crystal structure of the title compound, (I).
In the molecule of (I), (Fig. 1), the ligand bond lengths (Allen et al., 1987) and angles are within normal ranges. The atoms N and C9 lie in the benzene ring plane. The intramolecular C-H···O hydrogen bond (Table 1) results in the formation of a five-membered planar ring A (O1/C2/C3/C4/H4A), in which it is oriented with respect to the six-membered planar ring B (C3-C8) at a dihedral angle of A/B = 2.73 (3)°. So, they are also nearly coplanar.
In the crystal structure, intermolecular N-H···O hydrogen bonds (Table 1) link the molecules into chains elongated along the c axis and stacked along the b axis (Fig. 2), in which they may be effective in the stabilization of the structure.
After the solid has melted, concentrated sulfuric acid (16 ml, 300 mmol) was dropped from the dropping funnel at 363 K, the latter was treated with a mixture of ice and water. The product was filtered by suction. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of an ethanol solution.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH 2 ) and C-H = 0.93 and 0.96 Å for aromatic 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. Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. 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 Rfactors(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.