Mesit­yl(2,4,6-trimeth­oxy­phen­yl)borinic acid

Luliński, S.; Serwatowski, J.

doi:10.1107/S160053681002297X

Mesityl(2,4,6-trimethoxyphenyl)borinic acid

In the title molecule, C₁₈H₂₃BO₄, the dihedral angle between the least-squares planes of the aromatic rings is 84.88 (3)°. The B atom deviates by 0.202 (1) Å from the least-squares plane of the mesityl ring. All of the methoxy groups are approximately coplanar with the 2,4,6-trimethoxyphenyl ring, whereas the BOH group is twisted with respect to it by 19.5°. The borinic OH group is engaged in an intramolecular O—H

O hydrogen bond with one of ortho-methoxy groups. The molecular structure is stabilized by weak C—H

O contacts. In the crystal, molecules are linked by weak C—H

O and C—H

π interactions, generating a three-dimensional network.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S160053681002297X/pv2296sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S160053681002297X/pv2296Isup2.hkl Contains datablock I

CCDC reference: 786634

checkCIF report

Key indicators

Single-crystal X-ray study
T = 100 K
Mean (C-C) = 0.002 Å
R factor = 0.038
wR factor = 0.119
Data-to-parameter ratio = 19.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          3
PLAT480_ALERT_4_C Long H...A H-Bond Reported H21A   ..  O13     ..       2.79 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H10B   ..  O2      ..       2.61 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H12A   ..  O11     ..       2.79 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H12C   ..  O2      ..       2.84 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H21C   ..  O2      ..       2.82 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H21A   ..  O9      ..       2.85 Ang.
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600        163

Alert level G
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.61 mm

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   8 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   8 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

The ability of arylboronic acids to form supramolecular assemblies due to intermolecular hydrogen bonding is well known. The interest in our group has focused on ortho-alkoxyarylboronic acids (Dąbrowski et al., 2008; Luliński, 2008), which are related to the title compound, (I). It represents the first structural characterization of borinic acid possessing two different aryl rings. The molecular structure of (I) reflects the significant steric hindrance around the boron atom. The angle C3—B1—C15 is 126.90 (9)°, whereas the dihedral angle between the least squares planes of aryl groups is 84.88 (3)°. The boron atom is deviated from the least squares plane of the mesityl ring by 0.202 (1) Å. The borinic OH group is engaged in an intramolecular O—H···O hydrogen-bond with one of ortho-OMe groups. All OMe groups are approximately coplanar with the 2,4,6-trimethoxyphenyl ring, whereas the BOH group is significantly twisted with respect to it. Molecules are linked by C—H···O contacts, of which there are several types (Table 1). Finally, C—H···π interactions occur between ortho-OMe groups and the mesityl ring: the distances of H10A and H14A from the ring centroid are 2.79 Å and 2.88 Å, respectively (Tab. 1). As a result, a three-dimensional network is formed.

The crystal structures of several related arylborinic acids have been reported (Beringhelli et al., 2003; Cornet et al., 2003; Entwistle et al., 2007; Kuhlmann et al., 2008; Weese et al., 1987).

Related literature top

For background to ortho-alkoxyarylboronic acids, see: (Dąbrowski et al. 2008; Luliński (2008). For related structures, see: Beringhelli et al. (2003); Cornet et al. (2003); Entwistle et al. (2007); Kuhlmann et al. (2008); Weese et al. (1987).

Experimental top

A solution of 2-bromomesitylene (4.0 g) in THF (30 ml) was treated with n-BuLi (2.0 M solution in hexanes, 10 ml) at 198 K. The mixture was stirred for 15 min followed by the addition of (2,4,6-trimethoxyphenyl)diethoxyborane (5.30 g). The mixture was quenched with HCl (2.0 M solution in diethyl ether), 10 ml). The resulting suspension was filtered. Evaporation yielded an oil which was dissolved in hexane (30 ml). The solution was washed with water (5 ml). The solvent was removed and the residue was triturated with hexane (10 ml). The product was filtered and washed with hexane (10 ml). Crystals suitable for single-crystal X-ray diffraction analysis were grown by slow evaporation of a solution of (I) (0.2 g) in toluene (5 ml).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of (I) showing the atom-labelling scheme. The intramolecular hydrogen bond is shown as a dashed lines. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The crystal packing diagram for (I) showing hydrogen-bonding and CH-π interactions (dashed lines).

Mesityl(2,4,6-trimethoxyphenyl)borinic acid top

Crystal data top

C₁₈H₂₃BO₄	F(000) = 672
M_r = 314.17	D_x = 1.222 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 411 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 6.7775 (2) Å	Cell parameters from 19650 reflections
b = 13.0005 (4) Å	θ = 2.2–28.9°
c = 19.6234 (7) Å	µ = 0.08 mm⁻¹
β = 98.895 (3)°	T = 100 K
V = 1708.24 (10) Å³	Prismatic, colourless
Z = 4	0.61 × 0.40 × 0.17 mm

Data collection top

Oxford Diffraction KM-4-CCD diffractometer	4194 independent reflections
Radiation source: fine-focus sealed tube	3326 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.016
Detector resolution: 8.6479 pixels mm^-1	θ_max = 28.6°, θ_min = 3.0°
ω scan	h = −8→9
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2005)	k = −17→17
T_min = 0.93, T_max = 0.99	l = −26→26
28861 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.119	w = 1/[σ²(F_o²) + (0.0686P)² + 0.1911P] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max = 0.004
4194 reflections	Δρ_max = 0.37 e Å⁻³
216 parameters	Δρ_min = −0.25 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0075 (17)

Crystal data top

C₁₈H₂₃BO₄	V = 1708.24 (10) Å³
M_r = 314.17	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 6.7775 (2) Å	µ = 0.08 mm⁻¹
b = 13.0005 (4) Å	T = 100 K
c = 19.6234 (7) Å	0.61 × 0.40 × 0.17 mm
β = 98.895 (3)°

Data collection top

Oxford Diffraction KM-4-CCD diffractometer	4194 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2005)	3326 reflections with I > 2σ(I)
T_min = 0.93, T_max = 0.99	R_int = 0.016
28861 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.119	H-atom parameters constrained
S = 1.15	Δρ_max = 0.37 e Å⁻³
4194 reflections	Δρ_min = −0.25 e Å⁻³
216 parameters

Special details top

Experimental. Yield of (I) 3.5 g, m.p. 410 K. ¹H NMR (CDCl₃): 8.62 (br, 1 H), 6.75 (s, 2 H), 6.10 (s, 1 H), 3.85 (s, 3 H), 3.64 (s, 6 H), 2.28 (s, 3 H), 2.22 (s, 6 H) p.p.m.; ¹³C NMR: 167.8, 164.5, 137.4, 135.5, 126.3, 90.8, 55.6, 55.2, 21.7, 21.1 p.p.m.; ¹¹B NMR: 52.0 p.p.m..

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 F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
B1	0.23386 (18)	1.01129 (9)	0.18572 (6)	0.0181 (3)
O2	0.16799 (14)	1.03300 (6)	0.24658 (4)	0.0299 (2)
H2	0.1060	0.9820	0.2589	0.045*
C3	0.20989 (15)	0.89979 (8)	0.15476 (5)	0.0162 (2)
C4	0.06690 (16)	0.83008 (8)	0.17250 (5)	0.0172 (2)
C5	0.03526 (16)	0.73224 (8)	0.14369 (5)	0.0184 (2)
H5	−0.0666	0.6886	0.1556	0.022*
C6	0.15707 (17)	0.70085 (8)	0.09724 (5)	0.0188 (2)
C7	0.30614 (16)	0.76388 (8)	0.07894 (5)	0.0183 (2)
H7	0.3905	0.7404	0.0478	0.022*
C8	0.32920 (15)	0.86210 (8)	0.10719 (5)	0.0159 (2)
O9	−0.04374 (12)	0.86431 (6)	0.22104 (4)	0.0250 (2)
C10	−0.20118 (18)	0.80035 (9)	0.23876 (7)	0.0263 (3)
H10A	−0.2640	0.8343	0.2745	0.039*
H10B	−0.1457	0.7341	0.2561	0.039*
H10C	−0.3012	0.7891	0.1977	0.039*
O11	0.14219 (13)	0.60596 (6)	0.06627 (4)	0.0269 (2)
C12	0.0047 (2)	0.53478 (10)	0.08829 (7)	0.0334 (3)
H12A	0.0124	0.4692	0.0643	0.050*
H12B	−0.1311	0.5624	0.0776	0.050*
H12C	0.0384	0.5239	0.1382	0.050*
C14	0.59619 (17)	0.89498 (9)	0.04312 (6)	0.0228 (3)
H14A	0.6917	0.9494	0.0369	0.034*
H14B	0.5125	0.8802	−0.0011	0.034*
H14C	0.6689	0.8327	0.0602	0.034*
O13	0.47269 (11)	0.92799 (6)	0.09198 (4)	0.02081 (19)
C15	0.31889 (16)	1.10878 (8)	0.15189 (5)	0.0163 (2)
C16	0.50993 (16)	1.14768 (9)	0.17717 (6)	0.0208 (2)
C17	0.57168 (17)	1.24091 (9)	0.15249 (6)	0.0258 (3)
H17	0.7012	1.2663	0.1699	0.031*
C18	0.44838 (19)	1.29785 (9)	0.10304 (6)	0.0262 (3)
C19	0.26153 (18)	1.25828 (9)	0.07763 (6)	0.0236 (3)
H19	0.1761	1.2957	0.0434	0.028*
C20	0.19551 (16)	1.16476 (8)	0.10112 (5)	0.0185 (2)
C21	0.64605 (19)	1.08778 (10)	0.23081 (7)	0.0335 (3)
H21A	0.6503	1.0158	0.2163	0.050*
H21B	0.5957	1.0915	0.2749	0.050*
H21C	0.7808	1.1171	0.2361	0.050*
C22	0.5173 (2)	1.40011 (10)	0.07841 (8)	0.0414 (4)
H22A	0.5547	1.4457	0.1181	0.062*
H22B	0.4087	1.4316	0.0464	0.062*
H22C	0.6329	1.3893	0.0549	0.062*
C23	−0.00965 (18)	1.12497 (10)	0.07206 (6)	0.0274 (3)
H23A	−0.0908	1.1814	0.0496	0.041*
H23B	−0.0737	1.0969	0.1095	0.041*
H23C	0.0024	1.0708	0.0382	0.041*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
B1	0.0186 (6)	0.0170 (6)	0.0192 (6)	0.0006 (4)	0.0042 (4)	−0.0005 (5)
O2	0.0484 (6)	0.0182 (4)	0.0279 (5)	−0.0070 (4)	0.0214 (4)	−0.0055 (3)
C3	0.0181 (5)	0.0140 (5)	0.0167 (5)	0.0005 (4)	0.0034 (4)	0.0006 (4)
C4	0.0193 (5)	0.0158 (5)	0.0173 (5)	0.0027 (4)	0.0053 (4)	0.0020 (4)
C5	0.0206 (5)	0.0146 (5)	0.0204 (5)	−0.0024 (4)	0.0043 (4)	0.0027 (4)
C6	0.0255 (6)	0.0128 (5)	0.0172 (5)	−0.0004 (4)	0.0009 (4)	−0.0009 (4)
C7	0.0226 (5)	0.0169 (5)	0.0160 (5)	0.0007 (4)	0.0050 (4)	−0.0011 (4)
C8	0.0170 (5)	0.0154 (5)	0.0154 (5)	−0.0006 (4)	0.0024 (4)	0.0013 (4)
O9	0.0306 (5)	0.0161 (4)	0.0332 (5)	−0.0025 (3)	0.0208 (4)	−0.0010 (3)
C10	0.0287 (6)	0.0222 (6)	0.0319 (6)	−0.0031 (5)	0.0169 (5)	0.0047 (5)
O11	0.0402 (5)	0.0156 (4)	0.0275 (4)	−0.0085 (3)	0.0131 (4)	−0.0071 (3)
C12	0.0508 (8)	0.0184 (6)	0.0341 (7)	−0.0141 (5)	0.0166 (6)	−0.0074 (5)
C14	0.0221 (6)	0.0228 (6)	0.0262 (6)	−0.0004 (4)	0.0122 (5)	−0.0025 (5)
O13	0.0226 (4)	0.0178 (4)	0.0248 (4)	−0.0045 (3)	0.0124 (3)	−0.0048 (3)
C15	0.0184 (5)	0.0136 (5)	0.0179 (5)	0.0002 (4)	0.0061 (4)	−0.0043 (4)
C16	0.0189 (5)	0.0182 (5)	0.0257 (5)	0.0000 (4)	0.0055 (4)	−0.0069 (4)
C17	0.0207 (6)	0.0213 (6)	0.0377 (7)	−0.0067 (4)	0.0118 (5)	−0.0114 (5)
C18	0.0361 (7)	0.0157 (5)	0.0314 (6)	−0.0036 (5)	0.0199 (5)	−0.0033 (5)
C19	0.0339 (6)	0.0176 (5)	0.0212 (5)	0.0032 (5)	0.0107 (5)	0.0014 (4)
C20	0.0219 (5)	0.0171 (5)	0.0176 (5)	0.0008 (4)	0.0066 (4)	−0.0023 (4)
C21	0.0249 (6)	0.0304 (7)	0.0413 (7)	0.0023 (5)	−0.0073 (5)	−0.0058 (6)
C22	0.0577 (9)	0.0208 (6)	0.0523 (9)	−0.0102 (6)	0.0295 (7)	−0.0005 (6)
C23	0.0244 (6)	0.0293 (6)	0.0266 (6)	−0.0003 (5)	−0.0022 (5)	0.0013 (5)

Geometric parameters (Å, º) top

B1—O2	1.3675 (14)	C14—H14A	0.9800
B1—C3	1.5704 (15)	C14—H14B	0.9800
B1—C15	1.5803 (16)	C14—H14C	0.9800
O2—H2	0.8400	C15—C20	1.4014 (15)
C3—C4	1.4093 (14)	C15—C16	1.4070 (15)
C3—C8	1.4138 (14)	C16—C17	1.3933 (17)
C4—O9	1.3742 (13)	C16—C21	1.5051 (17)
C4—C5	1.3950 (15)	C17—C18	1.3919 (18)
C5—C6	1.3827 (15)	C17—H17	0.9500
C5—H5	0.9500	C18—C19	1.3863 (17)
C6—O11	1.3719 (13)	C18—C22	1.5128 (17)
C6—C7	1.3904 (15)	C19—C20	1.3981 (16)
C7—C8	1.3911 (15)	C19—H19	0.9500
C7—H7	0.9500	C20—C23	1.5103 (16)
C8—O13	1.3633 (12)	C21—H21A	0.9800
O9—C10	1.4372 (13)	C21—H21B	0.9800
C10—H10A	0.9800	C21—H21C	0.9800
C10—H10B	0.9800	C22—H22A	0.9800
C10—H10C	0.9800	C22—H22B	0.9800
O11—C12	1.4268 (14)	C22—H22C	0.9800
C12—H12A	0.9800	C23—H23A	0.9800
C12—H12B	0.9800	C23—H23B	0.9800
C12—H12C	0.9800	C23—H23C	0.9800
C14—O13	1.4325 (13)

O2—B1—C3	120.01 (10)	H14A—C14—H14C	109.5
O2—B1—C15	113.00 (9)	H14B—C14—H14C	109.5
C3—B1—C15	126.90 (9)	C8—O13—C14	117.95 (8)
B1—O2—H2	109.5	C20—C15—C16	118.65 (10)
C4—C3—C8	115.19 (9)	C20—C15—B1	119.92 (9)
C4—C3—B1	122.13 (9)	C16—C15—B1	121.04 (10)
C8—C3—B1	122.68 (9)	C17—C16—C15	119.98 (11)
O9—C4—C5	120.66 (9)	C17—C16—C21	120.57 (11)
O9—C4—C3	115.65 (9)	C15—C16—C21	119.45 (10)
C5—C4—C3	123.69 (9)	C18—C17—C16	121.65 (11)
C6—C5—C4	117.79 (10)	C18—C17—H17	119.2
C6—C5—H5	121.1	C16—C17—H17	119.2
C4—C5—H5	121.1	C19—C18—C17	118.03 (11)
O11—C6—C5	123.15 (10)	C19—C18—C22	121.41 (12)
O11—C6—C7	114.97 (10)	C17—C18—C22	120.56 (12)
C5—C6—C7	121.87 (10)	C18—C19—C20	121.69 (11)
C6—C7—C8	118.65 (10)	C18—C19—H19	119.2
C6—C7—H7	120.7	C20—C19—H19	119.2
C8—C7—H7	120.7	C19—C20—C15	119.98 (10)
O13—C8—C7	121.98 (9)	C19—C20—C23	119.75 (10)
O13—C8—C3	115.27 (9)	C15—C20—C23	120.26 (10)
C7—C8—C3	122.73 (9)	C16—C21—H21A	109.5
C4—O9—C10	119.04 (9)	C16—C21—H21B	109.5
O9—C10—H10A	109.5	H21A—C21—H21B	109.5
O9—C10—H10B	109.5	C16—C21—H21C	109.5
H10A—C10—H10B	109.5	H21A—C21—H21C	109.5
O9—C10—H10C	109.5	H21B—C21—H21C	109.5
H10A—C10—H10C	109.5	C18—C22—H22A	109.5
H10B—C10—H10C	109.5	C18—C22—H22B	109.5
C6—O11—C12	117.12 (9)	H22A—C22—H22B	109.5
O11—C12—H12A	109.5	C18—C22—H22C	109.5
O11—C12—H12B	109.5	H22A—C22—H22C	109.5
H12A—C12—H12B	109.5	H22B—C22—H22C	109.5
O11—C12—H12C	109.5	C20—C23—H23A	109.5
H12A—C12—H12C	109.5	C20—C23—H23B	109.5
H12B—C12—H12C	109.5	H23A—C23—H23B	109.5
O13—C14—H14A	109.5	C20—C23—H23C	109.5
O13—C14—H14B	109.5	H23A—C23—H23C	109.5
H14A—C14—H14B	109.5	H23B—C23—H23C	109.5
O13—C14—H14C	109.5

O2—B1—C3—C4	22.19 (16)	C7—C6—O11—C12	174.12 (10)
C15—B1—C3—C4	−154.17 (11)	C7—C8—O13—C14	2.63 (15)
O2—B1—C3—C8	−157.91 (10)	C3—C8—O13—C14	−178.89 (9)
C15—B1—C3—C8	25.73 (17)	O2—B1—C15—C20	−95.70 (12)
C8—C3—C4—O9	177.19 (9)	C3—B1—C15—C20	80.87 (14)
B1—C3—C4—O9	−2.90 (15)	O2—B1—C15—C16	77.06 (13)
C8—C3—C4—C5	−2.93 (15)	C3—B1—C15—C16	−106.37 (13)
B1—C3—C4—C5	176.97 (10)	C20—C15—C16—C17	1.03 (15)
O9—C4—C5—C6	−177.41 (10)	B1—C15—C16—C17	−171.82 (10)
C3—C4—C5—C6	2.72 (16)	C20—C15—C16—C21	−178.94 (10)
C4—C5—C6—O11	179.07 (10)	B1—C15—C16—C21	8.21 (16)
C4—C5—C6—C7	−0.35 (16)	C15—C16—C17—C18	0.20 (17)
O11—C6—C7—C8	178.98 (9)	C21—C16—C17—C18	−179.83 (11)
C5—C6—C7—C8	−1.55 (16)	C16—C17—C18—C19	−1.15 (17)
C6—C7—C8—O13	179.63 (9)	C16—C17—C18—C22	178.50 (11)
C6—C7—C8—C3	1.26 (16)	C17—C18—C19—C20	0.87 (17)
C4—C3—C8—O13	−177.59 (9)	C22—C18—C19—C20	−178.77 (11)
B1—C3—C8—O13	2.50 (15)	C18—C19—C20—C15	0.36 (16)
C4—C3—C8—C7	0.88 (15)	C18—C19—C20—C23	179.78 (10)
B1—C3—C8—C7	−179.03 (10)	C16—C15—C20—C19	−1.30 (15)
C5—C4—O9—C10	−3.75 (15)	B1—C15—C20—C19	171.63 (10)
C3—C4—O9—C10	176.13 (10)	C16—C15—C20—C23	179.28 (10)
C5—C6—O11—C12	−5.34 (16)	B1—C15—C20—C23	−7.79 (15)

Hydrogen-bond geometry (Å, º) top

Cg is the centroid of the C15–C20 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O9	0.84	1.92	2.6262 (11)	141
C21—H21A···O13	0.98	2.79	3.4825 (15)	128
C10—H10B···O2ⁱ	0.98	2.61	3.4920 (14)	149
C12—H12A···O11ⁱⁱ	0.98	2.79	3.5502 (15)	135
C12—H12C···O2ⁱ	0.98	2.84	3.6116 (17)	136
C21—H21C···O2ⁱⁱⁱ	0.98	2.82	3.5746 (16)	134
C21—H21A···O9ⁱⁱⁱ	0.98	2.85	3.6086 (15)	135
C10—H10A···Cg^iv	0.98	2.79	3.3266 (14)	115
C14—H14A···Cg^v	0.98	2.88	3.5988 (12)	130

Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x, −y+1, −z; (iii) x+1, y, z; (iv) x−1, −y+1/2, z−1/2; (v) x, y, z−1.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₃BO₄
M_r	314.17
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	6.7775 (2), 13.0005 (4), 19.6234 (7)
β (°)	98.895 (3)
V (Å³)	1708.24 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.61 × 0.40 × 0.17

Data collection
Diffractometer	Oxford Diffraction KM-4-CCD diffractometer
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2005)
T_min, T_max	0.93, 0.99
No. of measured, independent and observed [I > 2σ(I)] reflections	28861, 4194, 3326
R_int	0.016
(sin θ/λ)_max (Å⁻¹)	0.673

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.119, 1.15
No. of reflections	4194
No. of parameters	216
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.37, −0.25

Computer programs: CrysAlis CCD (Oxford Diffraction, 2005), CrysAlis RED (Oxford Diffraction, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), SHELXTL97 (Sheldrick, 2008).