1-(5,7-Dihy­droxy-2,2-dimethylchroman-6-yl)ethanone

In the title mol­ecule, C₁₃H₁₆O₄, the pyran ring is in a half-chair conformation. There is an intra­molecular hydrogen bond involving the ketone O atom and an H atom of a phenol group which forms an S(6) ring. The ketone O atom is also involved in an inter­molecular hydrogen bond with a different phenolic H atom of a symmetry-related mol­ecule, forming C(6) chains along the c-axis direction.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.032
• wR factor = 0.091
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found



Alert level C
STRVA01_ALERT_4_C           Flack test results are meaningless.
           From the CIF: _refine_ls_abs_structure_Flack    0.700
           From the CIF: _refine_ls_abs_structure_Flack_su    1.100
PLAT033_ALERT_4_C Flack x Parameter Value Deviates from Zero .....      0.700
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          3

Alert level G
REFLT03_ALERT_4_G  ALERT: MoKa measured Friedel data cannot be used to
                   determine absolute structure in a light-atom
                   study EXCEPT under VERY special conditions.
                   It is preferred that Friedel data is merged in such cases.
           From the CIF: _diffrn_reflns_theta_max           26.03
           From the CIF: _reflns_number_total               2366
           Count of symmetry unique reflns         1434
           Completeness (_total/calc)            164.99%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       932
           Fraction of Friedel pairs measured     0.650
           Are heavy atom types Z>Si present         no
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT032_ALERT_4_G Std. Uncertainty on Flack Parameter Value High .      1.100
PLAT916_ALERT_2_G Hooft y and Flack x Parameter values differ by .       0.90
PLAT917_ALERT_2_G The FCF is likely NOT based on a BASF/TWIN Flack          !

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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
   4 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The title compound was synthesized as an intermediate in the preparation of flavonoids or other phenolic derivatives and an intermediate for an anti-HIV chromanone (Kraus et al., 2011). It has also been obtained as a side product in the preparation of prenylated flavonoids with antitumour activity (Basabe et al., 2010). The molecular structure of the title compound is shown in Fig. 1. The pyran ring is in a half-chair conformation. There are two types of hydrogen bonds, one intramolecular and one intermolecular. The intramolecular O3—H103···O4 hydrogen bond forms an S(6) ring motif (Bernstein et al., 1995). This hydrogen bond motif is common to molecules which contain derivatized (2-hydroxyphenyl)ethanone structures (Chakkaravarthi et al., 2007). In addition to the intramolecular hydrogen bonding, there is an intermolecular hydrogen bond between the phenolic group and the ketone O atom of an adjacent molecule. This O2—H102···O4ⁱ (see Table 1 for symmetry code) hydrogen bond links the molecules to form infinite one-dimensional C(6) chains parallel to the c axis (base vector [0 0 1]). The same ketone oxygen atom therefore accepts two hydrogen bonds, one intermolecular and one intramolecular. The hydrogen bond lengths and bond angles are summarized in Table 1. Fig.2 depicts both the intermolecular and intramolecular hydrogen bonds. The length of intermolecular hydrogen bond is 0.303 Å shorter than the sum of the van der Waals radii. Although the length of hydrogen bonds does not necessarily correlate linearly with bond strength, due to packing constraints in the lattice, it is probable that this very short bond is moderate to strong. This is especially likely considering that the bond angle very closely approaches ideality.

Related literature

For applications of the title compound, see: Kraus et al. (2011); Basabe et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995). For a related structure, see: Chakkaravarthi et al. (2007).

S2. Experimental

To a solution of 6-hydroxy-2,4-dimethoxymethyloxy-3-prenylacetophenone (80 mg, 0.25 mmol) in methanol (20 ml) was added 1.0 M HCl (6 ml). The reaction mixture was refluxed for 1 h before cooling. The solvent was evaporated and the residue purified by column chromatography using hexane:ethyl acetate: 2:1 to afford 1-(5,7-dihydroxy-2,2-dimethylchroman-6-yl)ethanone as yellow crystals (10 mg, 17%): mp 501–502 K;

S3. Refinement

The positions of all hydrogen atoms bonded to C atoms were calculated using the standard riding model of SHELXL97 (Sheldrick, 2008) with C—H(aromatic) and C—H (methylene) distances of 0.93 Å and U_iso = 1.2 U_eq, and C—H(methyl) distances of 0.96 Å and U_iso = 1.5U_eq. The phenolic hydrogen atoms were located in the difference Fourier map and allowed to refine isotropically.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis CCD (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: WinGX (Farrugia, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. The molecular structure of the title compound with 50% probability ellipsoids. Hydrogen atoms have been rendered as spheres of arbitrary radius.
	Fig. 2. Part of a hydrogen bonded (dashed lines) chain along [001].

1-(5,7-Dihydroxy-2,2-dimethylchroman-6-yl)ethanone

Crystal data

C13H16O4	Dx = 1.312 Mg m^−3
Mr = 236.26	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P41212	Cell parameters from 2366 reflections
Hall symbol: P 4abw 2nw	θ = 2.9–26.0°
a = 10.5677 (2) Å	µ = 0.10 mm^−1
c = 21.4244 (5) Å	T = 298 K
V = 2392.6 (1) Å^3	Needle, colourless
Z = 8	0.6 × 0.4 × 0.4 mm
F(000) = 1008

Data collection

Oxford Diffraction Xcalibur 2 CCD diffractometer	2366 independent reflections
Radiation source: fine-focus sealed tube	2046 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 8.4190 pixels mm^-1	θmax = 26.0°, θmin = 2.9°
ω scans at fixed θ angles	h = −13→13
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −13→13
Tmin = 0.955, Tmax = 0.962	l = −26→26
26011 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.032	w = 1/[σ^2(Fo^2) + (0.0593P)^2 + 0.0612P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.091	(Δ/σ)max = 0.001
S = 1.08	Δρmax = 0.12 e Å^−3
2366 reflections	Δρmin = −0.11 e Å^−3
166 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0094 (18)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 931 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.7 (11)

Special details

Experimental. ¹H NMR (400 MHz, CD₃OD) 1.31 (2x 3H, s, C(CH₃)₂), 1.78 (2H, t, J = 6.7 Hz, CH₂), 2.55 (2H, t, J = 6.7 Hz, CH₂), 2.62 (3H, s, COCH₃), 5.77 (1H, s, ArH); ¹³C NMR 15.6 (C(CH₃)₂), 25.6 (2 × CH₂), 31.3 (C(CH₃)₂), 31.8 (COCH₃), 75.3 (C(CH₃)₂, 94.5 (C-5), 99.9 (C-1), 104.2 (C-3), 160.0, 160.9, 163.3 (C-2,4,6), 203.4 (COCH₃); ESITOFMS, m/z 259.0945 [M+Na]⁺ (calc. for C₁₃H₁₆NaO₄ 259.0946); IR (KBr) υ 2961 2918 2872 1654 1611 1433 1159 cm^-1.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
H102	1.1657 (18)	0.6538 (18)	0.1786 (9)	0.064 (5)*
H103	0.794 (2)	0.877 (2)	0.3250 (10)	0.075 (7)*
O1	0.94129 (10)	0.98280 (11)	0.09038 (5)	0.0540 (3)
O2	1.11831 (12)	0.66838 (11)	0.21655 (5)	0.0563 (3)
C9	0.93675 (14)	0.92341 (14)	0.14598 (6)	0.0410 (3)
O3	0.77624 (12)	0.92148 (12)	0.29235 (6)	0.0619 (3)
C7	1.03346 (13)	0.76254 (13)	0.20884 (7)	0.0390 (3)
O4	0.87361 (12)	0.75511 (12)	0.36008 (5)	0.0611 (4)
C8	1.02635 (13)	0.82754 (14)	0.15389 (7)	0.0403 (3)
H8	1.0815	0.8079	0.1215	0.048*
C4	0.85141 (14)	0.95417 (14)	0.19248 (7)	0.0452 (3)
C6	0.95010 (13)	0.79073 (13)	0.25928 (6)	0.0397 (3)
C12	0.95429 (15)	0.72843 (14)	0.31906 (7)	0.0468 (4)
C5	0.86024 (13)	0.88832 (13)	0.24823 (7)	0.0427 (3)
C1	0.83994 (17)	1.07167 (15)	0.07346 (8)	0.0553 (4)
C2	0.79788 (18)	1.14369 (17)	0.12997 (8)	0.0657 (5)
H2A	0.7282	1.1988	0.1186	0.079*
H2B	0.8670	1.1966	0.1444	0.079*
C3	0.75608 (18)	1.05776 (18)	0.18283 (9)	0.0670 (5)
H3A	0.7474	1.1067	0.2209	0.080*
H3B	0.6743	1.0211	0.1730	0.080*
C13	1.0503 (2)	0.6319 (2)	0.33569 (9)	0.0717 (6)
H13A	1.0384	0.6062	0.3783	0.108*
H13B	1.1334	0.6671	0.3308	0.108*
H13C	1.0412	0.5598	0.3088	0.108*
C10	0.9031 (2)	1.15856 (19)	0.02626 (9)	0.0774 (6)
H10A	0.9746	1.1991	0.0453	0.116*
H10B	0.8437	1.2216	0.0127	0.116*
H10C	0.9307	1.1098	−0.0090	0.116*
C11	0.7364 (2)	0.9942 (2)	0.04359 (11)	0.0801 (6)
H11A	0.7687	0.9537	0.0068	0.120*
H11B	0.6672	1.0485	0.0325	0.120*
H11C	0.7076	0.9311	0.0725	0.120*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0605 (7)	0.0550 (7)	0.0466 (6)	0.0166 (5)	−0.0064 (5)	0.0060 (5)
O2	0.0642 (7)	0.0578 (7)	0.0469 (6)	0.0220 (6)	0.0037 (5)	0.0064 (5)
C9	0.0420 (8)	0.0391 (8)	0.0418 (7)	0.0004 (6)	−0.0102 (6)	−0.0035 (6)
O3	0.0626 (7)	0.0610 (8)	0.0621 (8)	0.0078 (6)	0.0188 (7)	−0.0060 (6)
C7	0.0381 (7)	0.0363 (7)	0.0427 (7)	0.0005 (6)	−0.0055 (6)	−0.0035 (6)
O4	0.0725 (8)	0.0614 (7)	0.0495 (6)	−0.0088 (6)	0.0142 (6)	0.0021 (5)
C8	0.0384 (7)	0.0433 (8)	0.0393 (7)	0.0037 (6)	−0.0016 (5)	−0.0030 (6)
C4	0.0408 (8)	0.0400 (8)	0.0548 (8)	0.0043 (6)	−0.0045 (7)	−0.0072 (6)
C6	0.0425 (8)	0.0359 (7)	0.0406 (7)	−0.0070 (6)	−0.0024 (6)	−0.0052 (6)
C12	0.0533 (9)	0.0437 (8)	0.0433 (8)	−0.0129 (7)	−0.0015 (7)	−0.0023 (7)
C5	0.0388 (8)	0.0403 (7)	0.0492 (8)	−0.0038 (6)	0.0028 (6)	−0.0100 (6)
C1	0.0624 (10)	0.0412 (8)	0.0622 (10)	0.0110 (7)	−0.0207 (8)	0.0042 (7)
C2	0.0660 (11)	0.0489 (9)	0.0822 (12)	0.0191 (9)	−0.0169 (10)	−0.0018 (9)
C3	0.0609 (11)	0.0643 (11)	0.0758 (12)	0.0237 (9)	−0.0025 (9)	−0.0044 (9)
C13	0.0795 (13)	0.0825 (14)	0.0532 (10)	0.0105 (10)	0.0037 (9)	0.0208 (9)
C10	0.0952 (15)	0.0560 (11)	0.0811 (13)	0.0109 (11)	−0.0145 (11)	0.0178 (10)
C11	0.0806 (14)	0.0621 (11)	0.0975 (15)	0.0070 (11)	−0.0408 (12)	−0.0017 (11)

Geometric parameters (Å, º)

O1—C9	1.3471 (18)	C1—C2	1.497 (2)
O1—C1	1.4699 (18)	C1—C11	1.509 (3)
O2—C7	1.3496 (17)	C1—C10	1.520 (3)
O2—H102	0.97 (2)	C2—C3	1.517 (3)
C9—C4	1.383 (2)	C2—H2A	0.9700
C9—C8	1.397 (2)	C2—H2B	0.9700
O3—C5	1.3432 (18)	C3—H3A	0.9700
O3—H103	0.86 (2)	C3—H3B	0.9700
C7—C8	1.365 (2)	C13—H13A	0.9600
C7—C6	1.426 (2)	C13—H13B	0.9600
O4—C12	1.2566 (19)	C13—H13C	0.9600
C8—H8	0.9300	C10—H10A	0.9600
C4—C5	1.386 (2)	C10—H10B	0.9600
C4—C3	1.502 (2)	C10—H10C	0.9600
C6—C5	1.422 (2)	C11—H11A	0.9600
C6—C12	1.441 (2)	C11—H11B	0.9600
C12—C13	1.482 (2)	C11—H11C	0.9600
C9—O1—C1	119.33 (12)	C1—C2—C3	112.68 (15)
C7—O2—H102	111.0 (11)	C1—C2—H2A	109.1
O1—C9—C4	123.42 (14)	C3—C2—H2A	109.1
O1—C9—C8	114.90 (12)	C1—C2—H2B	109.1
C4—C9—C8	121.68 (13)	C3—C2—H2B	109.1
C5—O3—H103	106.8 (14)	H2A—C2—H2B	107.8
O2—C7—C8	120.88 (13)	C4—C3—C2	110.10 (15)
O2—C7—C6	118.15 (13)	C4—C3—H3A	109.6
C8—C7—C6	120.97 (13)	C2—C3—H3A	109.6
C7—C8—C9	120.46 (13)	C4—C3—H3B	109.6
C7—C8—H8	119.8	C2—C3—H3B	109.6
C9—C8—H8	119.8	H3A—C3—H3B	108.2
C9—C4—C5	117.34 (13)	C12—C13—H13A	109.5
C9—C4—C3	120.64 (15)	C12—C13—H13B	109.5
C5—C4—C3	121.99 (14)	H13A—C13—H13B	109.5
C5—C6—C7	115.98 (13)	C12—C13—H13C	109.5
C5—C6—C12	120.00 (13)	H13A—C13—H13C	109.5
C7—C6—C12	124.01 (13)	H13B—C13—H13C	109.5
O4—C12—C6	119.89 (15)	C1—C10—H10A	109.5
O4—C12—C13	116.79 (14)	C1—C10—H10B	109.5
C6—C12—C13	123.32 (14)	H10A—C10—H10B	109.5
O3—C5—C4	115.54 (14)	C1—C10—H10C	109.5
O3—C5—C6	120.90 (14)	H10A—C10—H10C	109.5
C4—C5—C6	123.56 (13)	H10B—C10—H10C	109.5
O1—C1—C2	109.98 (12)	C1—C11—H11A	109.5
O1—C1—C11	106.62 (13)	C1—C11—H11B	109.5
C2—C1—C11	113.80 (18)	H11A—C11—H11B	109.5
O1—C1—C10	103.32 (15)	C1—C11—H11C	109.5
C2—C1—C10	111.17 (15)	H11A—C11—H11C	109.5
C11—C1—C10	111.33 (16)	H11B—C11—H11C	109.5
C1—O1—C9—C4	−9.6 (2)	C9—C4—C5—O3	179.59 (12)
C1—O1—C9—C8	170.94 (13)	C3—C4—C5—O3	1.4 (2)
O2—C7—C8—C9	178.90 (13)	C9—C4—C5—C6	−1.1 (2)
C6—C7—C8—C9	0.0 (2)	C3—C4—C5—C6	−179.29 (14)
O1—C9—C8—C7	178.31 (12)	C7—C6—C5—O3	179.24 (13)
C4—C9—C8—C7	−1.2 (2)	C12—C6—C5—O3	−1.8 (2)
O1—C9—C4—C5	−177.76 (13)	C7—C6—C5—C4	0.0 (2)
C8—C9—C4—C5	1.7 (2)	C12—C6—C5—C4	178.93 (13)
O1—C9—C4—C3	0.5 (2)	C9—O1—C1—C2	36.82 (19)
C8—C9—C4—C3	179.93 (15)	C9—O1—C1—C11	−87.00 (18)
O2—C7—C6—C5	−178.34 (12)	C9—O1—C1—C10	155.56 (14)
C8—C7—C6—C5	0.6 (2)	O1—C1—C2—C3	−55.9 (2)
O2—C7—C6—C12	2.7 (2)	C11—C1—C2—C3	63.6 (2)
C8—C7—C6—C12	−178.32 (13)	C10—C1—C2—C3	−169.70 (14)
C5—C6—C12—O4	4.3 (2)	C9—C4—C3—C2	−19.4 (2)
C7—C6—C12—O4	−176.84 (14)	C5—C4—C3—C2	158.76 (15)
C5—C6—C12—C13	−175.88 (16)	C1—C2—C3—C4	47.0 (2)
C7—C6—C12—C13	3.0 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H102···O4^i	0.97 (2)	1.77 (2)	2.737 (2)	179 (1)
O3—H103···O4	0.86 (2)	1.71 (2)	2.501 (2)	151 (2)

Symmetry code: (i) y+1/2, −x+3/2, z−1/4.