5,3'-Dihydr­oxy-7,4'-dimethoxy­flavanone from Artemisia sphaerocephala Kraschen

The title compound, C₁₇H₁₆O₆, was isolated from the Chinese Tibetan medicinal plant Artemisia sphaerocephala Kraschen. The mol­ecular conformation is consolidated by two intra­molecular O-H...O hydrogen bonds. A further inter­molecular O-H...O hydrogen bond leads to chains along [010] in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.029
• wR factor = 0.078
• Data-to-parameter ratio = 7.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.46
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          3

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.00
           From the CIF: _reflns_number_total               1581
           Count of symmetry unique reflns         1585
           Completeness (_total/calc)             99.75%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT791_ALERT_1_G Confirm the Absolute Configuration of C2     ...          R
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

   2 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
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

As part of the ongoing investigations of the Chinese Tibetan medicinal plant Artemisia sphaerocephala Kraschen (Zhao et al., 2007), we now report the isolation and structure of the flavone-related title compound, (I).

Compound (I) consists of three-ring system, including a phenyl ring and a benzopyrone fused ring (Fig.1). The C–O bond distances range from 1.239 (2) to 1.453 (2) Å, in which C4–O2 [1.239 (2) Å] is typical for a C=O double-bond. The S(6) ring of O1/C2/C3/C4/C9/C10 in (I) is nonplanar, charactrtized by a O1–C2–C3–C4 torsion angle of 52.9 (2) °. Atom C2 is chiral, but the absolute structure of (I) could not be established from the present experiment. The dihedral angle between the aromatic ring planes is 77.26 (9) °.

Two intramolecular O-H···O hydrogen bonds (Table 1) help to establish the molecular conformation, both constructing S(6) rings. In addition, an intermolecular O-H···O link leads to [010] chains in the crystal (Fig. 2).

Related literature

For background, see: Zhao et al. (2007).

S2. Experimental

The air-dried whole plant (5.1 kg) was ground into powder and extracted three times with 95% EtOH for 3 h each time. The concentrated extract was dispersed in water and partitioned successively with petroleum ether, CHCl₃, EtOAC and n-BuOH. The chloroform fraction (115 g) was subjected to silics gel with petroleum ether-acetone (9:1) to yield two fractions (Frs. 1–2). Fraction 2 (50 g) was subjected to silics gel with petroleum ether-EtOAC (50:1, 45:1, 40:1, 30:1) to yield six fractions. After a week, the crude title compound (20 mg) was crystallized from the fourth fraction. After recrystallization from petroleum ether-EtOAC, colourless blocks of (I) arose, with a melting point of 475 K. The molecular formula, C₁₇H₁₆O₆, was established by ESIMS m/z:316(M+). Spectroscopic analysis, 1H NMR (400 MHz, DMSO-d6) δ: 12.15 (1H, s), 6.08 (1H, d, J=2.2 Hz), 6.05 (1H, d, J=2.2 Hz), 5.47 (1H, dd, J=12.6 Hz, 3.0 Hz), 3.20 (1H, dd, J=15.5 Hz, 12.6 Hz), 2.82 (1H, dd, J=15.5 Hz, 3.0 Hz); 13 C NMR (400 MHz, DMSO-d6) δ: 197.0 (C-4), 168.0 (C-7), 163.8 (C-5), 163.1 (C-9), 147.8 (C-4'), 146.7 (C-3'), 131.8 (C-1'), 117.9 (C-6'), 113.5 (C-5'), 111.3 (C-2'), 102.9 (C-10), 94.6 (C-6), 93.7 (C-8), 79.0 (C-2), 42.6 (C-3), 55.4 (4'-OCH₃), 55.3 (7-OCH₃).

S3. Refinement

Anomalous dispersion was negligible and Friedel pairs were merged before refinement.

The H atoms were geometrically placed (C-H = 0.93–0.98Å, O—H = 0.82 Å), and refined as riding with U_iso(H)=1.2U_eq(C) or U_iso(H)=1.5U_eq(O or methyl C).

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of (I), with displacement ellipsoids for the non-hydrogen atoms drawn at the 40% probability level. Hydrogen bonds are shown as double dashed lines.
	Fig. 2. Fragment of the one-dimensional chain structure of (I) with hydrogen bonds shown as dashed lines.

5,3'-Dihydroxy-7,4'-dimethoxyflavanone

Crystal data

C17H16O6	F(000) = 332
Mr = 316.30	Dx = 1.395 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2y b	Cell parameters from 4047 reflections
a = 5.4234 (12) Å	θ = 2.6–27.5°
b = 9.293 (2) Å	µ = 0.11 mm^−1
c = 14.940 (3) Å	T = 296 K
β = 91.039 (2)°	Block, colorless
V = 752.9 (3) Å^3	0.22 × 0.18 × 0.12 mm
Z = 2

Data collection

Bruker SMART APEX CCD diffractometer	1581 independent reflections
Radiation source: fine-focus sealed tube	1489 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
ϕ and ω scans	θmax = 26.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −6→6
Tmin = 0.977, Tmax = 0.987	k = −11→11
7958 measured reflections	l = −18→18

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.077	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0485P)^2 + 0.0531P] where P = (Fo^2 + 2Fc^2)/3
1581 reflections	(Δ/σ)max < 0.001
212 parameters	Δρmax = 0.11 e Å^−3
1 restraint	Δρmin = −0.14 e Å^−3

Special details

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	0.3993 (2)	0.73089 (16)	0.11833 (7)	0.0443 (3)
O2	0.8292 (3)	0.9824 (2)	0.28305 (11)	0.0697 (5)
O3	0.6055 (3)	0.8761 (2)	0.41875 (10)	0.0703 (5)
H3	0.7086	0.9231	0.3919	0.105*
O4	−0.0461 (3)	0.54437 (19)	0.35407 (9)	0.0532 (4)
O5	0.5698 (3)	0.79981 (18)	−0.28802 (9)	0.0582 (4)
O6	0.2587 (3)	0.94212 (19)	−0.18692 (9)	0.0595 (4)
H5	0.2732	0.9377	−0.2414	0.089*
C1'	0.6333 (3)	0.7757 (2)	−0.01135 (12)	0.0396 (4)
C2	0.6447 (3)	0.7700 (2)	0.08935 (12)	0.0407 (4)
H2	0.7605	0.6942	0.1079	0.049*
C2'	0.8030 (4)	0.7024 (2)	−0.06221 (12)	0.0469 (5)
H2'	0.9271	0.6494	−0.0338	0.056*
C3	0.7244 (4)	0.9111 (3)	0.13314 (13)	0.0509 (5)
H3A	0.8946	0.9310	0.1185	0.061*
H3B	0.6235	0.9889	0.1094	0.061*
C3'	0.7904 (4)	0.7070 (2)	−0.15510 (13)	0.0508 (5)
H3'	0.9056	0.6574	−0.1886	0.061*
C4	0.7001 (4)	0.9053 (2)	0.23342 (13)	0.0485 (5)
C4'	0.6070 (4)	0.7852 (2)	−0.19750 (12)	0.0434 (4)
C5	0.4695 (4)	0.7986 (2)	0.35954 (12)	0.0472 (5)
C5'	0.4376 (3)	0.8613 (2)	−0.14645 (12)	0.0415 (4)
C6	0.2845 (4)	0.7110 (3)	0.39144 (12)	0.0490 (5)
H6	0.2560	0.7047	0.4525	0.059*
C6'	0.4503 (3)	0.8559 (2)	−0.05446 (12)	0.0439 (4)
H6'	0.3359	0.9062	−0.0210	0.053*
C7	0.1420 (3)	0.6325 (2)	0.33055 (12)	0.0416 (4)
C7'	0.7267 (6)	0.7210 (3)	−0.34504 (14)	0.0701 (7)
H7'A	0.8943	0.7509	−0.3350	0.105*
H7'B	0.6798	0.7386	−0.4063	0.105*
H7'C	0.7120	0.6201	−0.3324	0.105*
C8	0.1841 (3)	0.6390 (2)	0.23879 (12)	0.0410 (4)
H8	0.0882	0.5852	0.1989	0.049*
C9	0.3691 (3)	0.7260 (2)	0.20815 (11)	0.0373 (4)
C10	0.5161 (3)	0.8091 (2)	0.26731 (12)	0.0413 (4)
C11	−0.1037 (5)	0.5297 (3)	0.44657 (14)	0.0660 (7)
H11A	0.0353	0.4893	0.4784	0.099*
H11B	−0.2436	0.4673	0.4525	0.099*
H11C	−0.1413	0.6225	0.4710	0.099*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0462 (7)	0.0580 (8)	0.0285 (6)	−0.0111 (6)	0.0003 (5)	0.0007 (6)
O2	0.0826 (11)	0.0731 (11)	0.0531 (9)	−0.0365 (10)	−0.0075 (8)	−0.0084 (8)
O3	0.0893 (12)	0.0821 (12)	0.0389 (7)	−0.0298 (10)	−0.0109 (7)	−0.0116 (8)
O4	0.0558 (8)	0.0709 (10)	0.0330 (7)	−0.0121 (7)	0.0052 (6)	0.0056 (7)
O5	0.0790 (10)	0.0625 (9)	0.0332 (7)	0.0170 (8)	0.0059 (6)	−0.0006 (7)
O6	0.0639 (9)	0.0755 (11)	0.0391 (8)	0.0270 (8)	−0.0006 (7)	0.0045 (8)
C1'	0.0429 (9)	0.0412 (10)	0.0346 (9)	−0.0019 (8)	0.0026 (7)	0.0034 (8)
C2	0.0407 (9)	0.0457 (10)	0.0357 (9)	−0.0013 (8)	−0.0004 (7)	0.0048 (8)
C2'	0.0465 (10)	0.0504 (11)	0.0438 (10)	0.0109 (9)	0.0036 (8)	0.0073 (9)
C3	0.0557 (11)	0.0530 (12)	0.0440 (11)	−0.0138 (10)	0.0009 (9)	0.0023 (9)
C3'	0.0552 (11)	0.0531 (12)	0.0446 (11)	0.0140 (10)	0.0117 (9)	0.0014 (10)
C4	0.0525 (11)	0.0484 (11)	0.0443 (10)	−0.0106 (10)	−0.0054 (9)	−0.0026 (9)
C4'	0.0561 (10)	0.0409 (10)	0.0334 (9)	0.0030 (9)	0.0069 (8)	0.0024 (8)
C5	0.0568 (11)	0.0521 (12)	0.0326 (9)	−0.0008 (10)	−0.0075 (8)	−0.0051 (8)
C5'	0.0443 (9)	0.0430 (10)	0.0372 (9)	0.0055 (8)	0.0010 (8)	0.0040 (8)
C6	0.0597 (11)	0.0605 (12)	0.0267 (8)	−0.0003 (10)	0.0001 (8)	−0.0005 (9)
C6'	0.0465 (10)	0.0484 (10)	0.0370 (9)	0.0089 (9)	0.0075 (8)	0.0013 (8)
C7	0.0422 (10)	0.0491 (11)	0.0335 (9)	0.0010 (8)	0.0014 (7)	0.0047 (8)
C7'	0.1016 (19)	0.0707 (16)	0.0385 (11)	0.0154 (15)	0.0164 (11)	−0.0066 (12)
C8	0.0409 (9)	0.0494 (10)	0.0326 (9)	−0.0038 (8)	−0.0039 (7)	−0.0016 (8)
C9	0.0405 (9)	0.0424 (10)	0.0290 (8)	0.0004 (8)	−0.0028 (7)	0.0007 (8)
C10	0.0450 (9)	0.0443 (10)	0.0346 (9)	−0.0016 (8)	−0.0031 (7)	−0.0011 (8)
C11	0.0706 (15)	0.0886 (18)	0.0393 (11)	−0.0062 (14)	0.0133 (10)	0.0150 (12)

Geometric parameters (Å, º)

O1—C9	1.3555 (19)	C3'—C4'	1.377 (3)
O1—C2	1.453 (2)	C3'—H3'	0.9300
O2—C4	1.239 (2)	C4—C10	1.439 (3)
O3—C5	1.350 (2)	C4'—C5'	1.397 (3)
O3—H3	0.8200	C5—C6	1.383 (3)
O4—C7	1.359 (2)	C5—C10	1.409 (3)
O4—C11	1.429 (2)	C5'—C6'	1.376 (2)
O5—C4'	1.370 (2)	C6—C7	1.390 (3)
O5—C7'	1.419 (3)	C6—H6	0.9300
O6—C5'	1.360 (2)	C6'—H6'	0.9300
O6—H5	0.8200	C7—C8	1.395 (2)
C1'—C2'	1.383 (3)	C7'—H7'A	0.9600
C1'—C6'	1.390 (3)	C7'—H7'B	0.9600
C1'—C2	1.506 (2)	C7'—H7'C	0.9600
C2—C3	1.525 (3)	C8—C9	1.373 (3)
C2—H2	0.9800	C8—H8	0.9300
C2'—C3'	1.389 (3)	C9—C10	1.409 (2)
C2'—H2'	0.9300	C11—H11A	0.9600
C3—C4	1.507 (3)	C11—H11B	0.9600
C3—H3A	0.9700	C11—H11C	0.9600
C3—H3B	0.9700
C9—O1—C2	115.53 (13)	C6—C5—C10	121.46 (17)
C5—O3—H3	109.5	O6—C5'—C6'	119.12 (16)
C7—O4—C11	119.06 (17)	O6—C5'—C4'	120.52 (16)
C4'—O5—C7'	117.54 (18)	C6'—C5'—C4'	120.37 (17)
C5'—O6—H5	109.5	C5—C6—C7	118.79 (17)
C2'—C1'—C6'	119.09 (16)	C5—C6—H6	120.6
C2'—C1'—C2	121.06 (16)	C7—C6—H6	120.6
C6'—C1'—C2	119.86 (16)	C5'—C6'—C1'	120.31 (17)
O1—C2—C1'	106.57 (13)	C5'—C6'—H6'	119.8
O1—C2—C3	109.97 (16)	C1'—C6'—H6'	119.8
C1'—C2—C3	113.88 (16)	O4—C7—C6	123.92 (16)
O1—C2—H2	108.8	O4—C7—C8	114.67 (16)
C1'—C2—H2	108.8	C6—C7—C8	121.40 (17)
C3—C2—H2	108.8	O5—C7'—H7'A	109.5
C1'—C2'—C3'	120.83 (17)	O5—C7'—H7'B	109.5
C1'—C2'—H2'	119.6	H7'A—C7'—H7'B	109.5
C3'—C2'—H2'	119.6	O5—C7'—H7'C	109.5
C4—C3—C2	111.48 (16)	H7'A—C7'—H7'C	109.5
C4—C3—H3A	109.3	H7'B—C7'—H7'C	109.5
C2—C3—H3A	109.3	C9—C8—C7	119.13 (17)
C4—C3—H3B	109.3	C9—C8—H8	120.4
C2—C3—H3B	109.3	C7—C8—H8	120.4
H3A—C3—H3B	108.0	O1—C9—C8	116.84 (16)
C4'—C3'—C2'	119.86 (17)	O1—C9—C10	121.70 (16)
C4'—C3'—H3'	120.1	C8—C9—C10	121.44 (15)
C2'—C3'—H3'	120.1	C5—C10—C9	117.77 (17)
O2—C4—C10	122.49 (18)	C5—C10—C4	121.68 (17)
O2—C4—C3	121.02 (19)	C9—C10—C4	120.51 (16)
C10—C4—C3	116.47 (17)	O4—C11—H11A	109.5
O5—C4'—C3'	126.74 (17)	O4—C11—H11B	109.5
O5—C4'—C5'	113.72 (17)	H11A—C11—H11B	109.5
C3'—C4'—C5'	119.53 (16)	O4—C11—H11C	109.5
O3—C5—C6	118.64 (17)	H11A—C11—H11C	109.5
O3—C5—C10	119.90 (18)	H11B—C11—H11C	109.5
C9—O1—C2—C1'	−177.36 (16)	C2'—C1'—C6'—C5'	0.5 (3)
C9—O1—C2—C3	−53.5 (2)	C2—C1'—C6'—C5'	−179.73 (18)
C2'—C1'—C2—O1	−128.91 (19)	C11—O4—C7—C6	−0.2 (3)
C6'—C1'—C2—O1	51.3 (2)	C11—O4—C7—C8	179.76 (19)
C2'—C1'—C2—C3	109.7 (2)	C5—C6—C7—O4	−179.2 (2)
C6'—C1'—C2—C3	−70.1 (2)	C5—C6—C7—C8	0.8 (3)
C6'—C1'—C2'—C3'	−0.8 (3)	O4—C7—C8—C9	179.50 (18)
C2—C1'—C2'—C3'	179.46 (18)	C6—C7—C8—C9	−0.6 (3)
O1—C2—C3—C4	52.9 (2)	C2—O1—C9—C8	−155.13 (17)
C1'—C2—C3—C4	172.44 (16)	C2—O1—C9—C10	26.5 (3)
C1'—C2'—C3'—C4'	0.0 (3)	C7—C8—C9—O1	−178.69 (17)
C2—C3—C4—O2	154.3 (2)	C7—C8—C9—C10	−0.3 (3)
C2—C3—C4—C10	−27.3 (3)	O3—C5—C10—C9	180.00 (19)
C7'—O5—C4'—C3'	3.6 (3)	C6—C5—C10—C9	−0.6 (3)
C7'—O5—C4'—C5'	−177.3 (2)	O3—C5—C10—C4	−2.5 (3)
C2'—C3'—C4'—O5	−179.8 (2)	C6—C5—C10—C4	176.9 (2)
C2'—C3'—C4'—C5'	1.1 (3)	O1—C9—C10—C5	179.19 (17)
O5—C4'—C5'—O6	−0.8 (3)	C8—C9—C10—C5	0.9 (3)
C3'—C4'—C5'—O6	178.4 (2)	O1—C9—C10—C4	1.6 (3)
O5—C4'—C5'—C6'	179.39 (18)	C8—C9—C10—C4	−176.67 (19)
C3'—C4'—C5'—C6'	−1.4 (3)	O2—C4—C10—C5	0.9 (3)
O3—C5—C6—C7	179.2 (2)	C3—C4—C10—C5	−177.44 (19)
C10—C5—C6—C7	−0.2 (3)	O2—C4—C10—C9	178.4 (2)
O6—C5'—C6'—C1'	−179.19 (19)	C3—C4—C10—C9	0.0 (3)
C4'—C5'—C6'—C1'	0.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.82	1.85	2.579 (2)	148
O6—H5···O5	0.82	2.18	2.640 (2)	116
O6—H5···O4^i	0.82	2.29	2.892 (2)	130

Symmetry code: (i) −x, y+1/2, −z.