1,3-Dimethyl 5-(4,4,5,5-tetra­methyl-1,3,2-dioxaborolan-2-yl)benzene-1,3-dicarboxyl­ate

Long-tao Yi; Zhi-qiang Liu

doi:10.1107/S1600536811054559

. 2012 Jan 7;68(Pt 2):o275. doi: 10.1107/S1600536811054559

1,3-Dimethyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzene-1,3-dicarboxylate

Long-tao Yi ^a,^*, Zhi-qiang Liu ^b

PMCID: PMC3274972 PMID: 22346917

Abstract

The title compound, C₁₆H₂₁BO₆, has has approximate C ₂ symmetry, but no crystallographically imposed molecular symmetry. In the crystal, molecules are packed into parallel columns along the a axis. Short intermolecular C—H⋯O contacts stabilize the crystal packing.

Related literature

For the synthesis of organoboronic esters, see: Kikuchi et al. (2008 ▶). For the synthesis of the title compound, see: Coventry et al. (2005 ▶).

Experimental

Crystal data

C₁₆H₂₁BO₆
M _r = 320.14
Orthorhombic,
a = 7.2163 (2) Å
b = 20.9627 (4) Å
c = 22.4624 (4) Å
V = 3397.96 (13) Å³
Z = 8
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
1.00 × 0.40 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.766, T _max = 0.982
22413 measured reflections
3864 independent reflections
2177 reflections with I > 2σ(I)
R _int = 0.043

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.142
S = 1.01
3864 reflections
215 parameters
H-atom parameters constrained
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XP in SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811054559/bt5730sup1.cif

e-68-0o275-sup1.cif^{(23.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811054559/bt5730Isup4.hkl

e-68-0o275-Isup4.hkl^{(185.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811054559/bt5730Isup3.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
C16—H16C⋯O4ⁱ	0.96	2.53	3.381 (3)	148

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

Arylboronic acids and arylborates are the key reagents in Suzuki-Miyaura coupling reaction. Transition metal-catalyzed C—H borylation of arenes is a direct, economical and environmentally kind method to synthesize organoboronic esters and is widely studied (Kikuchi et al., 2008). Recently, we have synthesized the title compound by direct Ir-catalyzed borylation and determined its X-ray structure.

The two meta-position methoxycarbonyl are almost co-planar with the benzene ring. The C—B bond is 1.556 (2) Å. Because the borolane ring adopts a somewhat twist conformation and C2, C9 atoms displace to opposite sides of the BO₂ plane, the title molecule has no crystallographic symmetry.

The molecules pack into columns along the a- axis uniformly and exhibit paralled patterns. Besides, there are some short intermolecular O···H (for example, O3···H8a, O4···H16c distances are 2.636 Å, 2.530 Å, respectively). We believe that these short intermolecular contacts are helpful for stabilization of the molecular packing in crystals.

Experimental

The title compound was synthesized via Ir-catalyzed borylation (Coventry et al., 2005) of diethyl isophthalate. Catalyst precursor [Ir(COD)]Cl]₂ (60 mg) and ligand dtbpy (4,4'-di-tert-bultyl-2,2'-dipyridyl) (120 mg) with a small amount of B₂pin₂ (pin=O₂C₂Me₄) ((160 mg) were loaded in a Schlenk tube and dissolved in 2 ml THF under argon. The mixture was stirred vigorously till the bluish violet solution turned to amaranthine. Then diethyl isophthalate (1.94 g, 10.0 mmol) and B₂pin₂ (2.54 g, 10.0 mmol) in 15 ml THF was added into this tube. The mixture was heated in oil bath at 80°C for 24 h. After cooling to room temperature, the mixture then went through a short silica pad to remove the residual Ir catalyst and the final compound was purified by column chromatography using dichloromethane, giving 2.56 g (80% yield) white crystalline product. Crystals were grown by slow evaporation of a hexane solution.