Partial cone conformer of 25,27-bis­[(methoxy­carbonyl)­meth­oxy]-26,28-dipropoxycalix[4]arene

Guo-Zhi Zhang; Mei Zhao; Xiao-Ling Zhang; Jian-Ping Ma; Dian-Shun Guo

doi:10.1107/S1600536808006843

. 2008 Mar 14;64(Pt 4):o712. doi: 10.1107/S1600536808006843

Partial cone conformer of 25,27-bis[(methoxycarbonyl)methoxy]-26,28-dipropoxycalix[4]arene

Guo-Zhi Zhang ^a, Mei Zhao ^a, Xiao-Ling Zhang ^a, Jian-Ping Ma ^a, Dian-Shun Guo ^a,^*

PMCID: PMC2960911 PMID: 21202103

Abstract

Molecules of the title compound, C₄₀H₄₄O₈, adopt a partial cone conformation. The dihedral angles between the planes of the aromatic rings and the mean plane through the methylene C atoms bridging the aromatic rings are 35.74 (7), 85.86 (5), 87.77 (4) and 89.95 (5)°. Two opposite aryl rings are approximately parallel to each other; the others are at an interplanar angle of 52.41 (6)°. Intra- and intermolecular C—H⋯O hydrogen bonds stabilize the molecular conformation and the crystal packing. Two C atoms of one propoxy chain are disordered over two positions; the site occupancy factors are ca 0.66 and 0.34.

Related literature

For related literature, see: Arena et al. (1997 ▶); Ferguson et al. (1993 ▶); Gutsche (1998 ▶); Iwamoto & Shinkai (1992 ▶); Pappalardo et al. (1992 ▶); Yamato et al. (1998 ▶).

Experimental

Crystal data

C₄₀H₄₄O₈
M _r = 652.75
Monoclinic,
a = 9.3007 (18) Å
b = 18.114 (4) Å
c = 20.768 (4) Å
β = 101.334 (3)°
V = 3430.6 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 298 (2) K
0.37 × 0.18 × 0.08 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: none
17798 measured reflections
6362 independent reflections
4677 reflections with I > 2σ(I)
R _int = 0.038

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.113
S = 1.04
6362 reflections
457 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 1999 ▶); cell refinement: SAINT (Bruker, 1999 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808006843/bt2681sup1.cif

e-64-0o712-sup1.cif^{(31.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808006843/bt2681Isup2.hkl

e-64-0o712-Isup2.hkl^{(311.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C30—H30B⋯O8ⁱ	0.96	2.58	3.406 (3)	144
C31—H31B⋯O5	0.97	2.40	2.859 (2)	109
C24—H24⋯O3ⁱⁱ	0.93	2.58	3.309 (3)	135
C21—H21A⋯O4	0.97	2.45	2.899 (2)	108
C21—H21A⋯O2	0.97	2.56	3.255 (3)	129
C10—H10C⋯O8ⁱⁱⁱ	0.96	2.59	3.510 (3)	161

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

Financial support from the National Natural Science Foundation of China (No. 20572064) and Shandong Province Natural Science Foundation (Y2006B30) is gratefully acknowledged.

supplementary crystallographic information

Comment

Substituted calix[4]arenes, as the most fascinating macrocyclic receptors in supramolecular chemistry, have attracted much interest in recent years due to the high affinity and ion selectivity (Gutsche, 1998). In particular, much attention was paid to the ethyl ester derivatives of the calix[4]arene (Iwamoto & Shinkai, 1992; Arena et al., 1997) since they are one of the most versatile intermediates for building highly preorganized receptors. It has been shown that the conformational distribution in the exhaustive O-alkylation of the calix[4]arene depends upon the reaction conditions, the para substituent of the calix[4]arene, and the steric requirement of the agent (Pappalardo et al., 1992; Ferguson et al., 1993). In the O-alkylation, the cone and 1,3-alternate conformers are often obtained via the metal template effect using potassium and caesium ions, respectively (Yamato et al., 1998). However, both partial cone and cone conformers were isolated instead of the 1,3-alternate conformer when treatment 25,27-dihydroxy-26,28-dipropoxycalix[4]arene with methyl bromoacetate using caesium carbonate as a base in acetone.

The title calix[4]arene compound adopts a partial cone conformation (Ferguson et al., 1993) (Fig. 1). The dihedral angles between the planes of the aromatic rings and the mean plane through the methylene C atoms bridging the aromatic rings are 35.74 (7), 85.86 (5), 87.77 (4) and 89.95 (5)°. The C2–C7 and C22–C27 rings make an interplanar angle of 52.41 (6)°. However the C12–C17 and C32–C37 rings are almost parallel to each other, with a dihedral angle of 4.17 (11)°. The O···O separations of ethereal O atoms are O1···O4 3.017 (2), O1···O5 3.365 (2), O4···O9 4.693 (2), and O5···O9 4.588 (2) Å. This conformation precludes any solvent molecule being enclathrated within the small molecular cavity.

In the crystal structure there are intra- and intermolecular C—H···O hydrogen bonds (Table 1), which stabilize the partial cone conformation and the crystal packing.

Experimental

A mixture of 25,27-dihydroxy-26,28-dipropoxycalix[4]arene (0.200 g, 0.39 mmol), anhydrous caesium carbonate (0.190 g, 0.59 mmol) and methyl bromoacetate (0.11 ml, 1.17 mmol) in dry acetone (10 ml) was refluxed under nitrogen for 8 h and cooled to room temperature. After removal of the solvent under reduced pressure, the residue was treated with 5% aqueous hydrochloric acid and extracted with dichloromethane. The organic layer was washed with saturated sodium hydrogen carbonate and brine, dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure and the residue was purified by flash column (silica gel, EtOAc/petroleum ether = 1:5) to give conformer (I) (R_f= 0.7) and comformer (II) (R_f= 0.4) in 48% and 39% yields, respectively. Single crystals suitable for X-ray diffraction analysis were obtained by slow diffusion of methanol into a dichloromethane solution at 273 K.