4-Amino-13-(1-naphthyl)-[2,2]paracyclophane

The title compound [systematic name: 12-amino-42-(1-naphthyl)-1,4(1,4)-dibenzenacyclohexaphane], C26H23N, was synthesized from 4-amino-13-bromo-[2,2]paracyclophane and 1-naphthaleneboronic acid in the presence of 1,4-dioxane. It is a new cyclophane-derived compound which can be regarded as a prospective ligand for asymmetric synthesis and catalysis. The benzene rings of the paracyclophane units are very slightly deformed from planarity as shallow boats.

Financial support from the National Natural Science Foundation of China (grant Nos. 20441004, 20671059)  The chemistry of [2.2]paracyclophanes has attracted the interest of researchers since the middle of the last century. After a standstill period, investigations in this area have received a new impulse (Cipiciani et al., 1997) and recently there has been notable progress especially regarding the synthesis of new derivatives. [2.2]paracyclophane is unique as the strain in the molecule has become so large that the benzene rings have been substantially bent from planarity. The configurationally rigid [2. 2]paracyclophanyl unit makes the design of chiral ligands of different types possible. The [2.2]paracyclophane ligand has previously been included in diphosphanes, (Pye et al., 1997) oxazoline-phosphanes, (Wu et al., 2003) oxazoline-imidazolium, (Bolm et al., 2003) oxazoline-selenides, (Hou et al., 2000) oxazoline-alcohols, (Wu et al., 2001) and Schiff base phenols.
The benzene rings in the [2,2] paracyclophane are not planar. Their conformation can be described as an asymmetric boat conformation. The benzene C atoms which are directly bonded to the ethylene links of the paracyclophane deviate significantly from the least-squares planes running through the other four benzene C atoms. The largest deviations are found for the atoms C3 [0.117 (5) Å] and C12 [0.146 (4) Å], which are the atoms closest to the amino and naphtyl substituents of the benzene rings. The angle between the planes through the benzene rings is 6.0 (2) °. The N1-C1 bond length lies between the expected values for a C-N and a C=N bond, which is probably caused by p-π conjugation.

S3. Refinement
All the H atoms could be found in the difference Fourier maps. Nevertheless, they were placed into the idealized positions and refined in a riding atom approximation with following constraints: C-H = 0.93, 0.97 Å and N-H = 0.86 Å, and with U iso (H) = 1.2U eq (C-aromatic and methylene and N-amido) in all the cases. In the absence of significant supporting information anomalous scattering effects, 1406 Friedel pairs were merged. The absolute configuration was determined by synthesis.

Figure 1
The structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.

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.