2,2-Dimethyl-N-(4-methylpyridin-2-yl)propanamide

In the title compound, C11H16N2O, the dihedral angle between the mean plane of the 4-methypyridine group and the plane of the amide link is 16.7 (1)°, and there is a short intramolecular C—H⋯O contact. Hydrogen bonding (N—H⋯O) between amide groups forms chains parallel to the b axis. Pairs of methylpyridine groups from molecules in adjacent chains are parallel but there is minimal π–π interaction.

In the title compound, C 11 H 16 N 2 O, the dihedral angle between the mean plane of the 4-methypyridine group and the plane of the amide link is 16.7 (1) , and there is a short intramolecular C-HÁ Á ÁO contact. Hydrogen bonding (N-HÁ Á ÁO) between amide groups forms chains parallel to the b axis. Pairs of methylpyridine groups from molecules in adjacent chains are parallel but there is minimalinteraction.

Structural commentary
Synthetic and naturally occurring pyridine derivatives have a broad range of biological activities (Thorat et al., 2013) including anticancer and antimicrobial (Abdel-Megeed et al., 2012) and anticoagulant (de Candia et al., 2013) properties.
Hence, pyridine derivatives are important compounds (Joule and Mills, 2000) and some synthetic approaches involve lithiation of 2-acylaminopyridines (Smith et al., 1995;Turner, 1983). The structures of a number of 2-acylaminopyridines have been determined (Mazik & Sicking, 2004;Mazik et al., 2004;Hodorowicz et al., 2007;Koch et al., 2008;Liang et al., 2008;Seidler et al., 2011). During research focused on new synthetic routes towards novel substituted pyridine derivatives (Smith et al., 1994;Smith et al., 1995;Smith et al., 1999;El-Hiti, 2003;Smith et al., 2012;Smith et al., 2013) we have synthesized the title compound in high yield. In the 4-methyl-2-pivaloylaminopyridine molecule ( Figure   1), the least squares plane through the 4-methypyridine group makes a dihedral angle of 16.7 (1)° with the plane through the amide link and a short intramolecular C5-H5···O1 contact is observed (Table 1). In the crystal structure ( Figure 2) N -H···O hydrogen bonding between amide groups forms chains parallel to the b axis. Pairs of methyl-pyridine groups in molecules from adjacent chains are parallel but there is minimal π-π interaction. The ring nitrogen is not involved in strong hydrogen bonding.

Synthesis and crystallization
To a cooled solution (0 °C) of 2-amino-4-methylpyridine (5.41 g, 50.0 mmol) and triethylamine (10 ml) in dichloromethane (DCM, 80 ml) pivaloyl chloride (6.63 g, 55.0 mmol) was slowly added in a drop-wise manner over 10 min. The reaction mixture was stirred at 0 °C for an extra 1 h. The mixture was poured into H 2 O (100 ml) and the organic layer was separated, washed with H 2 O (2 × 50 ml), dried (MgSO 4 ) and evaporated under reduced pressure to remove the solvent.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were positioned geometrically and refined using a riding model with U iso (H) = 1.2 times U eq for the atom they are bonded to except for the methyl groups where 1.5 times U eq was used with free rotation about the C-C bond.

Figure 1
A molecule showing atom labels and 50% probability displacement ellipsoids for non-H atoms.

Figure 2
Crystal structure packing showing NH..O hydrogen bonds as green dotted lines with the rest of the hydrogen atoms omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.16 e Å −3 Δρ min = −0.14 e Å −3 Extinction correction: SHELXL2013 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0037 (5) Special details Experimental. Absorption correction: CrysAlisPro (Agilent, 2014): Numerical absorption correction based on Gaussian integration over a multifaceted crystal model. Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.