(3aR,8aR)-2,2,6,6-Tetra­methyl-4,4,8,8-tetra­phenyl­tetra­hydro-1,3-dioxolo[4,5-e][1,3,2]dioxasilepine

Yousef M Hijji; Paul F Hudrlik; Anne M Hudrlik; Ray J Butcher; Jerry P Jasinski

doi:10.1107/S160053680804227X

. 2008 Dec 17;65(Pt 1):o135. doi: 10.1107/S160053680804227X

(3aR,8aR)-2,2,6,6-Tetramethyl-4,4,8,8-tetraphenyltetrahydro-1,3-dioxolo[4,5-e][1,3,2]dioxasilepine

Yousef M Hijji ^a, Paul F Hudrlik ^b, Anne M Hudrlik ^b, Ray J Butcher ^b,^*, Jerry P Jasinski ^c

PMCID: PMC2968053 PMID: 21581595

Abstract

The title compound, C₃₃H₃₄O₄Si, is a dioxasilepine compound, an effective chiral dopant for the determination of high helical twisting powers in liquid crystals. Its structure consists of a five-membered dioxolo ring fused to a seven-membered dioxasilepine ring which contains two sets of phenyl rings in a twisted butterfly shape attached to the two Csp ³ atoms in the ring opposite each other. Two methyl groups are attached to the Si atom in the ring and two additional methyl groups are attached to the Csp ³ atom in the dioxolo ring (one of which is disordered) and which lies in an envelope pattern. The dihedral angles between the mean planes of the phenyl ring pairs are 85.9 (2) and 83.5 (1)°. The dihedral angles between the mean planes of the dioxolo ring and the two pairs of butterfly shaped phenyl rings are 46.2 (1), 67.7 (1), 35.6 (7) and 83.5 (1)°.

Related literature

For a related structure, see: Madison et al. (1998 ▶). For dioxasilepines as chiral dopants in liquid crystals, see: Kuball & Hofer (2000 ▶); Kuball et al. (1997 ▶). For puckering parameters and pseudo rotation parameters, see: Cremer & Pople (1975 ▶); Rao et al. (1981 ▶).

Experimental

Crystal data

C₃₃H₃₄O₄Si
M _r = 522.69
Orthorhombic,
a = 10.008 (2) Å
b = 17.081 (3) Å
c = 17.271 (3) Å
V = 2952.4 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 (2) K
0.56 × 0.32 × 0.16 mm

Data collection

Siemans P2 diffractometer
Absorption correction: refined from ΔF (SHELXL97; Sheldrick, 2008 ▶) T _min = 0.786, T _max = 0.982
2819 measured reflections
2819 independent reflections
1693 reflections with I > 2σ(I)
3 standard reflections every 97 reflections intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.119
S = 1.04
2819 reflections
388 parameters
14 restraints
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: XSCANS (Siemens, 2000 ▶); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680804227X/hg2455sup1.cif

e-65-0o135-sup1.cif^{(27.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680804227X/hg2455Isup2.hkl

e-65-0o135-Isup2.hkl^{(138.4KB, hkl)}

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

supplementary crystallographic information

Comment

Dioxasilepine compounds have been found to be effective chiral dopants for the determination of high helical twisting powers in liquid crystals (Kuball et al. 2000 and 1997). We have synthesized a new related structure and its crystal structure is reported.

The title compound, C₃₃H₃₄O₄Si, consists of a 5-membered oxolo ring fused to a 7-membered dioxasilepine ring which contains two sets of phenyl rings in a twisted butterfly shape attached to the two sp³ carbon atoms in the ring opposite each other (Fig. 1). Two methyl groups are attached to the silicon atom in the ring and two additional methyl groups are attached to the sp³ carbon atom in the dioxolo ring (one of which is disordered at C4) which lies in an envelope pattern on C1 with pseudo rotation parameters P and Tau(M) of 172° and 18.5°, respectively (Rao et al., 1981) for the refine bond C1—O2 [puckering parameters θ(2) = 0.1695 Å, Phi(2) = 80.2586° (Cremer & Pople, 1975)]. The dihedral angle between the mean planes of phenyl rings C11–C16 and C21–C26 is 85.9 (2)^o and between phenyl rings C31–C36 and C41–C46 is 83.5 (1)^o. Dihedreal angles between the mean planes of the dioxolo ring and the two butterfly shaped phenyl rings are 46.2 (1)^o [C11–C16], 67.7 (1)^o [C21–C26], 35.6 (7)^o [C31–C36] and 83.5 (1)^o [C41–C46], respectively.

Crystal packing is influenced by intermolecular C5A—H5A···Cg3 [3.628 (1) Å, x, y, z] and C4A—H4AA···Cg5 [3.757 (7) Å, x, y, z] π ring interactions where Cg3 and Cg5 = center of gravity of phenyl rings C21–C26 and C41–46, respectively (Fig. 2).

Experimental

The title compound was synthesized by adding 0.13 g (1.06 mmol) of dimethylaminopyridine to a solution of 0.50 g (1.07 mmol) of (-)-trans-α,α'-(dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanol) (TADDOL) in 20 ml of anhydrous ether (distilled from Na/benzophenone) under nitrogen atmosphere at room temperature. Then 0.145 g of imidazole (2.14 mmol) was added. The mixture was stirred to get a homogeneous solution. A solution of 0.138 g (1.07 mmol) dichlorodimethylsilane (distilled from CaH₂) in 40 ml of anhydrous ether was added dropwise to the above solution. The mixture was stirred overnight under a nitrogen atmosphere. A white precipitate formed. The solid was filtered off through a sintered glass funnel under a blanket of nitrogen gas. Slow evaporation of the solvent under a stream of nitrogen gave white crystals (0.35 g; 62.5%). m.p 483–485 K. ¹H NMR (CDCl₃, CH₂Cl₂ standard, 300 MHz) δ 7.62, 7.60 (appears as d, J = 8 Hz, 4 H, Ar), 7.25–7.05 (m, 16 H, Ar), 5.15 (s, 2H, CH(OR), 0.52 (s, 6 H, CMe₂), -0.25 (s, 6 H, SiMe₂). ¹³C NMR (CDCl₃, 75 MHz) δ 147.5, 143.1, 129.0, 127.9, 127.2, 127.1, 126.81, 126.76, 113.9, 82.2, 81.6, 27.0, -0.13.