6,7-Bis(bromomethyl)-2,11,18,21,24,27-hexaoxatetracyclo[26.4.0.04,9.012,17]dotriaconta-1(28),4,6,8,12(17),13,15,29,31-nonaene dichloromethane monosolvate

The title 20-crown-6 unit, C28H30Br2O6·CH2Cl2, consisting of three benzo groups and triethylene glycol was prepared from the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene and bisphenol in the presence of sodium hydride. In the crystal, one O atom of the central ethylene glycol in the triethylene glycol unit exhibits an exo conformation as a result of intramolecular C—H⋯O hydrogen bonds. The crown unit and the solvent molecule are linked by weak C—H⋯O hydrogen bonds.

The title 20-crown-6 unit, C 28 H 30 Br 2 O 6 ÁCH 2 Cl 2 , consisting of three benzo groups and triethylene glycol was prepared from the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene and bisphenol in the presence of sodium hydride. In the crystal, one O atom of the central ethylene glycol in the triethylene glycol unit exhibits an exo conformation as a result of intramolecular C-HÁ Á ÁO hydrogen bonds. The crown unit and the solvent molecule are linked by weak C-HÁ Á ÁO hydrogen bonds.
supplementary materials   (Sim et al., 2001, Lee et al., 2009, we reported the preparation of new crown ether and its solidstate structure, which could be a precursor of the common-nuclear biscrown ether, bearing three aromatic subunits.
Herein, we report the crystal structure of the title compound.
In the title molecule ( Fig. 1), in the A-to-B ring and A-to-C ring connectivities, the torsion angles C4-C5-O1-C6 and C25-C24-O6-C23 are 169.4 (5)° and 101.4 (7)°, respectively, which indicate that the A ring is situated trans to B ring, but situated gauche to C ring, with dihedral angles of 41.7 (2)° between A and B and 85.5 (2)° between A and C. The dihedral angle between B and C rings is 78.2 (2)°. The all C-C-O-C torsion angles except C17-C16-O4-C15(87.4 (8)°) in the triethylene glycol group exhibit trans conformation.
In the title compound, O4 atom of two oxygen atoms (O3 and O4) of triethylene glycol group is in an exo-orientation, whereas O3 is in an endo-orientation. In general, oxygen atoms of ethylene glycol groups in crown ether-based compounds would favor endo-orientation (Wolf et al., 1987). Exo conformation of the O4 atom is due to the intramolecular C-H···O hydrogen bonds ( Fig. 1 & Table 1). In addition, the crown unit and the solvent molecule are linked by weak intermolecular C-H···O hydrogen bonds ( Fig. 1 & Table 1).

Experimental
To a refluxing suspension of sodium hydride (5.50 mmol) in THF under nitrogen was added dropwise a solution of 1,2,4,5-tetrakis(bromomethyl)benzene (2.20 mmol) and 1,8-bis(2-hydroxyphenoxy)-3,6-dioxaoctane (2.00 mmol) in THF over a period of 3 h. The mixture was then refluxed for an additional 24 h. After cooling to room temperature, 10% aqueous hydrochloric acid was added. The solvent was removed under reduced pressure and the residual mixture was extracted with dichloromethane. The organic layer was washed with water, dried over anhydrous magnesium sulfate, and evaporated in vacuo. The crude product was chromatographed on a silica-gel column using a mixed solvent of ethyl acetate and n-hexane (1:1) as eluent, and recrystallization from dichloromethane/n-hexane (1:20, v/v) gave as a crystalline solid in 49% yield (m.p. 373 K).

Refinement
All H-atoms were positioned geometrically and refined using a riding model with d(C-H)=0.95 Å, U iso =1.2U eq (C) for aromatic and 0.99 Å, U iso =1.2U eq (C) for CH 2 atoms.

Figure 1
The molecular structure of the title compound with the atom numbering scheme and C-H···O interactions (dotted lines).  ), 3.82 (t, 4 H, ArOCH 2 CH 2 OCH 2 ) and 3.63 (s, 4 H, ArOCH 2 CH 2 OCH 2 ). 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.