{[2-Methyl-2-(phenoxymethyl)propane-1,3-diyl]bis(oxy)}dibenzene

The title compound, C23H24O3, was obtained in a one-step (60% yield) synthesis from 1,1,1-tris(hydroxymethyl)ethane. It features a tripodal ligand capable of complexing metal centres. One of the three conformations involving the methyl group, the central C—C bond and the phenoxy substituents is antiperiplanar while the two others are synclinal [the corresponding C—C—C—O torsion angles are −174.6 (1), −53.2 (2) and −47.3 (2)°]. In the crystal, C—H⋯O interactions link the molecules into [010] chains.

The title compound, C 23 H 24 O 3 , was obtained in a one-step (60% yield) synthesis from 1,1,1-tris(hydroxymethyl)ethane. It features a tripodal ligand capable of complexing metal centres. One of the three conformations involving the methyl group, the central C-C bond and the phenoxy substituents is antiperiplanar while the two others are synclinal [the corresponding C-C-C-O torsion angles are À174.6 (1), À53.2 (2) and À47.3 (2) ]. In the crystal, C-HÁ Á ÁO interactions link the molecules into [010] chains. 236 parameters H-atom parameters constrained Á max = 0.16 e Å À3 Á min = À0.14 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).  ,α,α-tris(hydroxymethyl)ethane has been widely used in the design of polypodal ligands (Viguier et al., 2001;Alajarín et al., 2007;Beaufort et al., 2007) capable of forming stable complexes with transition metals [Cu(I), Cu(II), Ni(II), Pd(II), Y(III)] and a variety of lanthanide(III) cations (La 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ ). The main step in the preparation of such compounds involves nucleophilic displacement of the hydroxyl group with various nucleophiles. The hydroxyl group is initially converted to a tosylate (Beaufort et al., 2007) or a halogen (Alajarín et al., 2007) before the substitution step is carried out. The title compound provides a related tripodal ligand that can be readily synthesized in a single step and in good yield. In the course of investigating its use as a tripodal ligand in transition metal complexation reactions, we examined its structure to determine the preferred conformation, identify the principal intermolecular interactions, and extract detailed geometric information.

Related literature
Initial attempts to prepare the title compound by reacting phenol or sodium phenoxide with α,α,α-tris[(4-tolylsulfonyl)methyl]ethane or α,α,α-tris(chloromethyl)ethane were unsuccessful due to the poor nucleophilic character of phenol and its alkali metal salts. However, converting α,α,α-tris(hydroxymethyl)ethane to the corresponding trifluoromethanesulfonate derivative gave a more effective substrate with a much superior leaving group ability. Thus, the latter derivative reacted with sodium phenoxide under very mild conditions to afford the title compound in 60% isolated yield. The only remarkable short intermolecular contact is a C-H···O interaction.

Experimental
Preparation of (2-methyl-2-(phenoxymethyl)propane-1,3-diyl)bis(oxy)dibenzene 1,1,1-tris-(hydroxymethyl)ethane (600 mg, 5 mmol) was dissolved in pyridine (10 ml) and cooled to 273K in an ice/water bath. The colorless solution was treated dropwise over ten minutes with trifluoromethanesulfonic anhydride in THF (30 ml) at 273K. Phenol (4.23 g, 45 mmol) was added in portions to the stirred suspension over 1 h. The trifluoromethanesulfonate solution was then slowly added to the sodium phenoxide solution at 273K to give a light reddish yellow color. The ice bath was removed and the mixture was subsequently stirred overnight at room temperature. The mixture was diluted with diethyl ether (50 ml) and the ether layer was washed with 5% HCl solution (3 x 20 ml), 1 N solution of NaOH (3 x 20 ml), saturated NaCl solution (3 x 20 ml), dried (Na 2 SO 4 ) and concentrated in vacuo. 1 H NMR analysis of the crude indicated that it consisted of a 2:1 mixture of the product and corresponding disubstituted analogue.
The residue was initially chromatographed (elution with 90% hexanes-ethyl acetate) to provide an unseparated mixture of the aforementioned products. Further chromatographic separation with hexanes and re-crystallization (hexanes)

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radius. 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 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.