1-[4-(3,5-Di­methoxy-2-methyl­phenoxy)-2,6-di­hydroxy-3-methyl­phenyl]­ethanone

The benzene rings of the title compound, C₁₈H₂₀O₆, are nearly perpendicular to each other [dihedral angle 75.2 (1)°]. The two methoxy groups and the acetyl group are almost coplanar to their attached benzene rings. One hydroxyl group is involved in an intramolecular O—H...O hydrogen bond with the adjacent acetyl O atom. The crystal structure is stabilized by intermolecular O—H...O contacts.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.084
• wR factor = 0.228
• Data-to-parameter ratio = 13.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

It has been reported that p-depsides could be readily converted into the corresponding diphenyl ether via an intramolecular Smiles rearrangement (Elix et al., 1984). A number of depsides have been prepared as intermediate compounds in the synthesis of corresponding diphenyl ether molecules. Suitable reaction conditions for an intramolecular Smiles rearrangement of the prepared depsides have also been studied extensively (Elix & Jenie, 1989; Elix et al., 1990). The crystal structure determination of the title compound, (I), was undertaken as part of structural studies on diphenyl ether derivatives. Knowledge of the three-dimensional structure of the title molecule could be useful for the understanding of this synthesis. The NMR spectrum of the obtained product did not show the signal ranged from 11 to 14 p.p.m., an indication of a predicting intramolecular hydrogen bonding between hydroxyl and acetyl group, where as the X-ray data did strongly prove.

This structure is similar to 2-(4-acetyl-3,5-dihydroxy-2-methylphenoxy)-4,6-dimethoxy-3-methylbenzoic acid (Chantrapromma et al., 2000). A displacement ellipsoid plot with the numbering scheme is shown in Fig. 1. The bond lengths and angles observed in the structure are normal and agree reasonably with the reported values (Elix et al., 1978; Allen et al., 1987; Chantrapromma et al., 1998, 2000). The benzene rings are nearly perpendicular to each other [dihedral angle 75.2 (1)°]. The two methoxy groups and the acetyl group are nearly coplanar with the benzene rings [C18—O6—C11—C10 172.8 (3)°, C17—O5—C9—C10 5.4 (4)° and C2—C3—C13—C14 - 0.2 (5)°]. There are two hydroxyl groups in a molecule involved in hydrogen bonding: one hydroxyl group, O4—H4A, involved as a donor in an intramolecular hydrogen bond with the O3 acetyl group acting as acceptor, the other, O2—H2A, involved in an intermolecular hydrogen bond with the O6 methoxy group of an adjacent molecule.

S2. Experimental

To a solution of 2-(3,5-dihydroxy-4-acetyl-2-methylphenoxy)-4,6-dimethoxy-3-methylbenzoic acid (0.16 mmol) in anhydrous THF was added methyl lithium (1.95 mmol). The mixture was kept and stirred at 273 K for 3 h and at room temperature for an additional 6 h. The reaction mixture was acidified with cold diluted saturated ammonium chloride (30 ml) and extracted with ether. The residue was purified by preparative thin-layer chromatography with 20% hexane/chloroform as eluent to give colorless solids of the title compound (m.p. 462–463 K). Suitable crystals for X-ray data collection were recrystallized from a chloroform and ethyl acetate mixed solvent. It was difficult to get a good quality crystal since the title compound is air sensitive.

S3. Refinement

Crystal decay was monitored by SAINT (Siemens, 1996) and was found to be negligible. After checking their presence in the difference map, all H atoms were geometrically fixed and allowed to ride on their attached atoms. Due to large fraction of weak data at higher angles, the 2θ maximum is limited to 54°.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 1990).

Figures

Fig. 1. The structure of dimeric title compound showing 50% probability displacement ellipsoids and the atom-numbering scheme.

1-[4-(3,5-Dimethoxy-2-methylphenoxy)-2,6-dihydroxy-3-methylphenyl]ethanone

Crystal data

C18H20O6	F(000) = 352
Mr = 332.34	Dx = 1.338 Mg m^−3
Triclinic, P1	Melting point = 189–190 K
a = 7.4228 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.1460 (1) Å	Cell parameters from 2684 reflections
c = 11.3559 (3) Å	θ = 1.8–28.3°
α = 102.474 (1)°	µ = 0.10 mm^−1
β = 90.989 (2)°	T = 293 K
γ = 98.544 (2)°	Slab, light yellow
V = 824.70 (3) Å^3	0.44 × 0.22 × 0.18 mm
Z = 2

Data collection

Siemens SMART CCD area-detector diffractometer	1615 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.063
Graphite monochromator	θmax = 25.0°, θmin = 1.8°
Detector resolution: 8.33 pixels mm^-1	h = −4→8
ω scans	k = −12→12
4715 measured reflections	l = −13→13
2864 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.084	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.228	w = 1/[σ^2(Fo^2) + (0.1109P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
2864 reflections	Δρmax = 0.38 e Å^−3
218 parameters	Δρmin = −0.43 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.040 (9)

Special details

Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0,88 and 180°) for the crystal and each exposure of 30 s covered 0.3° in ω. The crystal-to-detector distance was 4.023 cm and the detector swing angle was -35°. Coverage of the unit set is 98.3% complete.

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.5200 (3)	0.20725 (19)	0.65299 (15)	0.0415 (6)
O2	0.7590 (3)	0.6820 (2)	0.70228 (17)	0.0489 (6)
H2A	0.7433	0.6789	0.7730	0.073*
O3	0.8717 (3)	0.6111 (2)	0.33808 (18)	0.0527 (7)
O4	0.7490 (3)	0.3659 (2)	0.32010 (16)	0.0495 (6)
H4A	0.7946	0.4356	0.2996	0.074*
O5	0.8189 (3)	0.1038 (2)	0.98373 (18)	0.0550 (7)
O6	0.2931 (3)	0.3248 (2)	1.05203 (17)	0.0487 (6)
C1	0.6446 (4)	0.4466 (3)	0.6810 (2)	0.0353 (7)
H1A	0.6201	0.4623	0.7625	0.042*
C2	0.7219 (4)	0.5531 (3)	0.6314 (2)	0.0339 (7)
C3	0.7615 (4)	0.5322 (3)	0.5078 (2)	0.0335 (7)
C4	0.7159 (4)	0.3960 (3)	0.4388 (2)	0.0349 (7)
C5	0.6389 (4)	0.2866 (3)	0.4865 (2)	0.0334 (7)
C6	0.6037 (4)	0.3158 (3)	0.6086 (2)	0.0335 (7)
C7	0.5343 (4)	0.2155 (3)	0.7788 (2)	0.0349 (7)
C8	0.6755 (4)	0.1603 (3)	0.8216 (2)	0.0366 (7)
C9	0.6786 (4)	0.1615 (3)	0.9461 (2)	0.0373 (7)
C10	0.5526 (4)	0.2175 (3)	1.0206 (2)	0.0390 (7)
H10A	0.5598	0.2194	1.1028	0.047*
C11	0.4138 (4)	0.2716 (3)	0.9716 (2)	0.0367 (7)
C12	0.4025 (4)	0.2696 (3)	0.8487 (2)	0.0377 (7)
H12A	0.3091	0.3037	0.8151	0.045*
C13	0.8413 (4)	0.6396 (3)	0.4478 (3)	0.0378 (7)
C14	0.8896 (5)	0.7863 (3)	0.5130 (3)	0.0554 (9)
H14A	0.9396	0.8398	0.4577	0.083*
H14B	0.9782	0.7937	0.5776	0.083*
H14C	0.7821	0.8194	0.5454	0.083*
C15	0.5973 (5)	0.1436 (3)	0.4073 (2)	0.0441 (8)
H15A	0.5435	0.0813	0.4543	0.066*
H15B	0.7083	0.1158	0.3758	0.066*
H15C	0.5139	0.1433	0.3416	0.066*
C16	0.8184 (5)	0.1018 (4)	0.7429 (3)	0.0549 (9)
H16A	0.7949	0.1089	0.6613	0.082*
H16B	0.8149	0.0075	0.7454	0.082*
H16C	0.9367	0.1518	0.7720	0.082*
C17	0.8266 (6)	0.0905 (4)	1.1062 (3)	0.0600 (10)
H17A	0.9308	0.0492	1.1205	0.090*
H17B	0.7176	0.0341	1.1215	0.090*
H17C	0.8364	0.1792	1.1591	0.090*
C18	0.1609 (5)	0.3959 (4)	1.0102 (3)	0.0611 (10)
H18A	0.0863	0.4278	1.0753	0.092*
H18B	0.0855	0.3352	0.9454	0.092*
H18C	0.2223	0.4725	0.9819	0.092*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0656 (15)	0.0349 (11)	0.0236 (9)	−0.0001 (10)	0.0010 (10)	0.0112 (8)
O2	0.0765 (17)	0.0332 (11)	0.0345 (10)	0.0052 (11)	0.0085 (11)	0.0040 (9)
O3	0.0762 (17)	0.0501 (13)	0.0386 (11)	0.0136 (12)	0.0180 (12)	0.0210 (10)
O4	0.0768 (17)	0.0451 (13)	0.0292 (10)	0.0119 (12)	0.0169 (11)	0.0109 (9)
O5	0.0661 (16)	0.0755 (16)	0.0346 (11)	0.0413 (14)	0.0040 (11)	0.0158 (11)
O6	0.0600 (15)	0.0622 (14)	0.0339 (11)	0.0345 (12)	0.0088 (10)	0.0151 (10)
C1	0.0433 (17)	0.0395 (16)	0.0248 (12)	0.0087 (14)	0.0032 (13)	0.0094 (12)
C2	0.0412 (17)	0.0336 (15)	0.0292 (13)	0.0113 (13)	0.0008 (13)	0.0087 (12)
C3	0.0380 (17)	0.0392 (16)	0.0298 (13)	0.0159 (13)	0.0060 (13)	0.0150 (12)
C4	0.0428 (17)	0.0429 (17)	0.0247 (12)	0.0180 (14)	0.0072 (13)	0.0121 (12)
C5	0.0396 (17)	0.0376 (16)	0.0266 (13)	0.0126 (13)	0.0040 (12)	0.0105 (12)
C6	0.0399 (17)	0.0373 (16)	0.0279 (13)	0.0118 (14)	0.0019 (12)	0.0132 (12)
C7	0.0534 (19)	0.0321 (15)	0.0210 (12)	0.0035 (14)	0.0045 (13)	0.0117 (11)
C8	0.0455 (18)	0.0356 (15)	0.0303 (13)	0.0066 (14)	0.0083 (13)	0.0100 (12)
C9	0.0440 (18)	0.0392 (16)	0.0325 (14)	0.0133 (14)	0.0021 (13)	0.0119 (12)
C10	0.0528 (19)	0.0421 (17)	0.0275 (13)	0.0155 (15)	0.0046 (14)	0.0138 (13)
C11	0.0505 (19)	0.0361 (16)	0.0275 (13)	0.0133 (14)	0.0085 (14)	0.0108 (12)
C12	0.0492 (19)	0.0372 (16)	0.0318 (14)	0.0120 (15)	−0.0029 (14)	0.0153 (12)
C13	0.0362 (17)	0.0461 (18)	0.0376 (15)	0.0152 (14)	0.0099 (13)	0.0167 (13)
C14	0.071 (3)	0.0428 (19)	0.0556 (19)	0.0049 (18)	0.0146 (19)	0.0194 (16)
C15	0.060 (2)	0.0381 (17)	0.0323 (14)	0.0052 (16)	0.0024 (15)	0.0044 (13)
C16	0.058 (2)	0.070 (2)	0.0381 (16)	0.0190 (19)	0.0088 (16)	0.0066 (16)
C17	0.083 (3)	0.073 (2)	0.0364 (16)	0.046 (2)	−0.0027 (17)	0.0156 (16)
C18	0.062 (2)	0.076 (2)	0.055 (2)	0.041 (2)	0.0038 (18)	0.0135 (18)

Geometric parameters (Å, º)

O1—C6	1.379 (3)	C3—C13	1.465 (4)
O1—C7	1.414 (3)	C4—C5	1.391 (4)
O2—C2	1.366 (3)	C5—C6	1.391 (4)
O3—C13	1.250 (3)	C5—C15	1.518 (4)
O4—C4	1.351 (3)	C7—C12	1.373 (4)
O5—C9	1.373 (4)	C7—C8	1.386 (4)
O5—C17	1.428 (3)	C8—C9	1.411 (4)
O6—C11	1.374 (3)	C8—C16	1.505 (4)
O6—C18	1.432 (4)	C9—C10	1.375 (4)
C1—C2	1.379 (4)	C10—C11	1.397 (4)
C1—C6	1.389 (4)	C11—C12	1.393 (4)
C2—C3	1.417 (4)	C13—C14	1.500 (4)
C3—C4	1.422 (4)
C6—O1—C7	118.6 (2)	C1—C6—C5	122.5 (3)
C9—O5—C17	118.1 (2)	C12—C7—C8	124.6 (2)
C11—O6—C18	118.2 (2)	C12—C7—O1	118.2 (3)
C2—C1—C6	119.6 (2)	C8—C7—O1	117.0 (3)
O2—C2—C1	119.5 (2)	C7—C8—C9	115.7 (3)
O2—C2—C3	119.0 (2)	C7—C8—C16	123.5 (3)
C1—C2—C3	121.5 (2)	C9—C8—C16	120.8 (3)
C2—C3—C4	116.0 (3)	O5—C9—C10	124.5 (3)
C2—C3—C13	124.9 (3)	O5—C9—C8	113.5 (3)
C4—C3—C13	119.1 (2)	C10—C9—C8	122.0 (3)
O4—C4—C5	115.9 (2)	C9—C10—C11	119.4 (3)
O4—C4—C3	120.4 (3)	O6—C11—C12	123.6 (3)
C5—C4—C3	123.7 (2)	O6—C11—C10	115.7 (2)
C4—C5—C6	116.7 (3)	C12—C11—C10	120.7 (3)
C4—C5—C15	120.5 (2)	C7—C12—C11	117.6 (3)
C6—C5—C15	122.8 (3)	O3—C13—C3	120.2 (3)
O1—C6—C1	121.7 (2)	O3—C13—C14	117.2 (3)
O1—C6—C5	115.8 (2)	C3—C13—C14	122.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···O6^i	0.82	2.02	2.837 (3)	179
O4—H4A···O3	0.82	1.74	2.482 (3)	149

Symmetry code: (i) −x+1, −y+1, −z+2.