Diethyl 4,5-diphenyl-3,6-bis­(trimethyl­sil­yl)benzene-1,2-dicarboxyl­ate

Jing Zhang; Hongmei Qu; Zhenyu Zhang; Lishan Zhou

doi:10.1107/S160053681102397X

. 2011 Jun 30;67(Pt 7):o1864. doi: 10.1107/S160053681102397X

Diethyl 4,5-diphenyl-3,6-bis(trimethylsilyl)benzene-1,2-dicarboxylate

Jing Zhang ^a, Hongmei Qu ^a,^*, Zhenyu Zhang ^a, Lishan Zhou ^b

PMCID: PMC3152123 PMID: 21837228

Abstract

In the title compound, C₃₀H₃₈O₄Si₂, the two phenyl rings are twisted away from the central benzene ring by 70.28 (8) and 67.42 (7)°. The two Si atoms attached to the benzene ring deviate in opposite directions from the ring plane by 0.258 (3) and 0.206 (3) Å, respectively. One ethyl group is disordered over two conformations in a 0.568 (5):0.432 (5) ratio. The crystal packing exhibits weak intermolecular C—H⋯O interactions.

Related literature

For general background to the synthesis of benzene compounds, see: Reppe & Schweckendiek (1948 ▶); Reppe et al. (1948 ▶); Schore (1988 ▶); Vollhardt (1984 ▶); Yamamoto (2005 ▶). For related structures, see: Haberecht et al. (2002 ▶); Takahashi et al. (2006 ▶).

Experimental

Crystal data

C₃₀H₃₈O₄Si₂
M _r = 518.78
Triclinic,
a = 11.534 (2) Å
b = 12.389 (3) Å
c = 12.853 (3) Å
α = 63.40 (3)°
β = 67.63 (3)°
γ = 65.99 (3)°
V = 1455.1 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 113 K
0.20 × 0.18 × 0.12 mm

Data collection

Rigaku Saturn CCD area-detector diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005 ▶) T _min = 0.970, T _max = 0.982
12066 measured reflections
6772 independent reflections
3380 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.127
S = 0.95
6772 reflections
338 parameters
4 restraints
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.38 e Å⁻³

Data collection: CrystalClear (Rigaku/MSC, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; 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 datablock(s) I, global. DOI: 10.1107/S160053681102397X/cv5108sup1.cif

e-67-o1864-sup1.cif^{(27.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681102397X/cv5108Isup2.hkl

e-67-o1864-Isup2.hkl^{(331.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681102397X/cv5108Isup3.cml

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
C10—H10B⋯O1	0.98	2.39	3.116 (3)	131
C27—H27B⋯O4	0.98	2.43	3.137 (3)	129

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Acknowledgments

The authors gratefully acknowledge the State Key Laboratory of Elemento-Organic Chemistry (Nankai University) for the data collection.

supplementary crystallographic information

Comment

The synthesis of benzene compounds is an important activity in organic chemistry. Reppe and colleagues (Reppe & Schweckendiek, 1948; Reppe et al., 1948) first discovered the Ni-catalyzed cyclization of acetylene affording benzene in 1948. Since then, Vollhardt et al. (1984), Schore (1988), Yamamoto (2005) and many others developed the chemistry of transition metal complexes-mediated or catalyzed cyclotrimerization of alkynes. The title compound (I) has been prepared by zirconocene-mediated cyclization of 1-phenyl-2- trimethylsilyl acetylene and diethyl acetylenedicarboxylate (DEAD). Herewith we present its crystal structure.

In (I) (Fig.1), the C1—Si1 and C4—Si2 bond lengths of 1.921 (2) and 1.923 (2) Å, respectively, are slightly longer than those in p-bis(trimethylsilyl)benzene [1.882 (1) Å] (Haberecht et al., 2002). The lengths of the C—Si and C—O bonds in (I) agree with the corresponding values in 1,4-bis(trimethylsilyl)-2,3-bis(methoxycarbonyl)-9,10-dihydroanthracene (Takahashi et al., 2006). It seems that the bond lengths are influenced by the steric hindrance of substituents on the central benzene ring. In the title molecule, there are three benzene rings - A (C1—C6), B (C13—C18) and C (C19—C24), respectively. Rings B and C are twisted from the central benzene ring A at 67.42 (7) and 70.28 (8)°, respectively. The Si1 and Si2 atoms attached to benzene ring deviate from its plane in opposite directions at 0.206 (3) and 0.258 (3) Å, respectively.

The crystal packing exhibits weak intermolecular C—H···O interactions (Table 1).

Experimental

The title compound (I) has been prepared by zirconocene-mediated cyclization of 1-phenyl-2- trimethylsilyl acetylene and diethyl acetylenedicarboxylate (DEAD) (see Fig. 2). To a solution of Cp₂ZrCl₂ (350 mg, 1.20 mmol) in 10 ml of THF was added n-BuLi (1.56 M hexane solution, 1.54 ml, 2.40 mmol) at -78 °C, and the mixture was stirred for 15 min. The solution was warmed to -40°C for 30 min and then re-cooled to -78°C. After 15 min, 1-phenyl-2-trimethylsilyl acetylene (393 µL, 2.0 mmol) was added to the solution, and it was warmed to room temperature. After stirring for 3 h, CuCl (297 mg, 3.0 mmol) and diethyl acetylenedicarboxylate (DEAD) (0.477 ml, 3.0 mmol) were added to the mixture, and it was stirred for 6 h at room temperature. The mixture was quenched with 3 N HCl and extracted with ethyl acetate. The combined organic phase was washed with water, saturated aqueous NaHCO₃ solution, and brine. The solution was dried over anhydrous Na₂SO₄. The solvent was evaporated, and the resulting solid was purified by a flash chromatography (silica gel, hexane: ethyl acetate =5:1 as eluent) to afford mixture of the title compound I and II. When mixture was heated in toluene at 100 °C for 3 h, benzene I (424 mg) was obtained in 82% yield as pale yellow solid. ¹H NMR (CDCl3, Me4Si): -0.14 (s, 18 H), 1.41 (t, J = 6.9 Hz, 6 H), 4.29–4.36 (q, J = 7.2 Hz, 4 H), 6.78–6.81 (m, 4 H), 7.00–7.08 (m, 6 H); ¹³C NMR (CDCl3, Me4Si): 1.7, 13.8, 61.8, 126.7, 126.9, 131.3, 137.9, 138.0, 142.0, 149.6, 170.5. HRMS (EI) calc. for C₃₀H₃₈O₄Si₂: 518.2309. Found: 518.2314. The solid of compound (I) was re-crystallized by ethanol to give colorless single crystals of (I), suitable for X-ray analysis.