7,11,15,28-Tetramethyl-1,21,23,25-tetrakis(2-phenylethyl)resorcin[4]arene ethyl acetate clathrate

The title compound, C68H64O8·C4H8O2, is a new resorcin[4]arene cavitand synthetic precursor, obtained by alkylation of a previously reported resorcin[4]arene. The additional alkyl bridges significantly rigidify the structure and enforce a ‘bowl’ shape on the molecular cavity. In the crystal structure, the molecule lies on a crystallographic mirror plane, and a single ethyl acetate molecule (also lying on the mirror plane) is present within the compound cavity, illustrating the host capabilities of the molecule.

The title compound, C 68 H 64 O 8 ÁC 4 H 8 O 2 , is a new resorcin[4]arene cavitand synthetic precursor, obtained by alkylation of a previously reported resorcin [4]arene. The additional alkyl bridges significantly rigidify the structure and enforce a 'bowl' shape on the molecular cavity. In the crystal structure, the molecule lies on a crystallographic mirror plane, and a single ethyl acetate molecule (also lying on the mirror plane) is present within the compound cavity, illustrating the host capabilities of the molecule.

S2. Experimental
The synthesis of the resorcin[4]arene octol precursor can proceed via two different synthetic approaches. The older protocol as set out by Cram et al. (1988) involves heating a solution of the resorcin[4]arene starting material and the CH 2 BrCl in the presence of K 2 CO 3 at atmospheric pressure. Reaction proceeds over a number of days, often accompanied by addition of further equivalents of the alkylating reagent. However, since CH 2 BrCl is volatile and boils at 341 K, the reaction temperature is limited to a range between 333 and 343 K. This results in yields of 40-60%. More recently, Roman et al. (1999) reported a procedure which made use of a sealed tube as a reaction vessel, heated to 361 K. The reagents are heated in the presence of Cs 2 CO 3 , which is used instead of K 2 CO 3 due to the templating ability of the caesium cation, which aids in the formation of macrocyclic assemblies such as cavitands (Piepers & Kellog, 1978).
Under these conditions, yields are in excess of 80%; indeed, the use of the protocol of Kaifer et al. in the synthesis of the resorcin[4]arene octol precursor gave a yield of 92%.
To prepare the title compound (Scheme 2): dry resorcin[4]arene octol (1.00 g, 1.66 mmol) and Cs 2 CO 3 (3.00 g, 9.21 mmol) were added with stirring to dry DMSO (10 ml) in a pressure tube (ACE pressure tube, Aldrich). To the resulting pink solution, CH 2 BrCl (3.00 ml, 46.0 mmol) was added followed by further DMSO (10 ml). The tube was sealed and heated at 360 K for 16 h. After cooling to room temperature, the tube contents were poured into 2% HCl (200 ml) and the voluminous solid formed was filtered and washed with water. The cream coloured solid was chromatographed on silica gel using a mobile phase of 70:30 hexane-ethyl acetate (R f = 0.59). The fractions collected were concentrated on a rotary evaporator to yield a cream coloured solid. The solid was stirred in methanol overnight, and filtered to yield the product as a white powder (0.97 g, 92%, m.p. 418-420 K). Crystals suitable for X-ray diffraction analysis were grown by slow liquid diffusion of methanol into a solution of the title compound in 1:1 ethyl acetate:hexane.

S3. Refinement
H atoms were visible in difference Fourier maps but were positioned geometrically and allowed to ride on their respective parent atoms, with C-H bond lengths of 1.00 (CH), 0.99 (CH 2 ), or 0.98 (CH 3 ) Å. They were then refined with a riding model with U iso (H) = 1.2U eq (C) or 1.5U eq (CH 3 ). One of the phenylethyl 'feet′ was found to be disordered and was refined over two positions using isotropic displacement parameters and with SADI, SIMU, DELU, DFIX and SADI restraints applied. The refined site occupancy factors for the two positions are 0.461 (5) and 0.539 (5), respectively.  The molecular structure with displacement ellipsoids drawn at the 50% probability level. H atoms are omitted. The "bowl" shape of the molecule is evident, with the ethyl acetate molecule present as a guest in the molecular cavity.   The formation of the title compound. 7,11,15,28-Tetramethyl-1,21,23,25-tetrakis(2-phenylethyl)-2,20:3,19-dimetheno-1H,21H,23H,25H-  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.