tert-Butyl N-{4-[N-(4-hydroxyphenyl)carbamoyl]benzyl}carbamate

In the title compound, C19H22N2O4, the dihedral angle between the aromatic rings is 67.33 (2)°. In the crystal, molecules are linked through N—H⋯O and O—H⋯O hydrogen bonds, generating a two-dimensional network lying parallel to (100). As a result of the twist of the molecular skeleton and the hindrance of the tert-butyl groups, no π–π interactions exist between the aromatic rings.

In the title compound, C 19 H 22 N 2 O 4 , the dihedral angle between the aromatic rings is 67.33 (2) . In the crystal, molecules are linked through N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds, generating a two-dimensional network lying parallel to (100). As a result of the twist of the molecular skeleton and the hindrance of the tert-butyl groups, nointeractions exist between the aromatic rings. H atoms treated by a mixture of independent and constrained refinement Á max = 0.15 e Å À3 Á min = À0.16 e Å À3 Table 1 Hydrogen-bond geometry (Å , ). (100) plane was formed (Fig. 2). The network planes packed with weak van de Walss interactions (Fig. 3), where all tertbutyl moieties are in one side of the network plane and interacted with the tert-butyl moieties of the neighbor plane, and although the aromatic backbones are face to face packed, there are not π-π interactions between the aromatic rings because of the twist of the skeletons.
Then the solution was concentrated under vacuum to about 30 ml. 100 ml of 5% NaHCO 3 solution was added to the solution then the solution was extracted with dichloromethane (30 ml × 3). The water layer was acidified by 3 N HCl until pH ≈ 4 then white precipitate appeared. The precipitate was filtrated, washed with water, and dried to get white solid of N-Boc protected 4-(aminomethyl)benzoic acid (BAMBZA), 2.39 g (yield: 95%).

Refinement
H atoms on the tert-butyl moiety were placed at idealized positions of CH 3 group and refined as riding atoms with U iso (H) = 1.5 × U eq (C). Other H atoms were located in a difference Fourier map and refined isotropically, with C-H distances in

Figure 1
The crystal structure of (I), drawn with 30% probability displacement ellipsoids. Hydrogen atoms are shown as spheres of arbitrary radii.  Packing of the planar networks. All hydrogen atoms are omitted for clarity.

Special details
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. 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.