(E)-6-Methoxy-3-(α-methoxybenzyl­idene)benzo[b]furan-2(3H)-one at 173 K

The title compound, C₁₇H₁₄O₄, is an unprecedented new synthetic isoaurone-type enol ether that has the E configuration. The planar furanone ring is fused to a methoxy­benzene ring system, with an interplanar angle of 175.7 (1)°. Due to this ring fusion, the six-membered ring has a significant amount of ring strain, as shown by the internal ring angle range of 115.8 (1)–124.7 (1)°, whereas the vinylic phenyl ring has internal angles between 119.7 (1) and 120.2 (1)°. The mol­ecules form infinite hydrogen-bonding layers along the b direction of the form C—H...O, where the keto O atom acts as a bifurcated acceptor. These layers are connected along the c direction by another hydrogen bond with a methoxy H atom as donor. In addition to this connection, the layers are stacked via centres of symmetry by a pair of symmetry-related benzo­furan­one ring systems.

S1. Comment

Isoaurones [3-arylidenebenzofuran-2(3H)ones] are an uncommon class of flavonoid compound isomeric with aurones [2-arylidenebenzofuran-3(2H)-ones], some of which are naturally occurring, e.g. E-marginalin (Barbier, 1987). Like the aurones, isoaurones can exist in either the E– or the Z-form. This class of compound has been of synthetic interest over the years (Gripenberg & Juselius, 1954; Walter et al., 1966; Moriarty et al., 1984; Litinas & Stampelos, 1992; Rossi et al., 1995). In the course of our studies in the flavonoid field we have synthesized the unusual title isoaurone type enol ether compound, (II) (Burke & O'Sullivan, 1997) via lactonization and subsequent dehydration of (2R,3R)-2-hydroxy-2-(2-hydroxy-4-methoxyphenyl)-3-methoxy-3-phenylpropan-1-oic acid, (I). \scheme

We have determined on the basis of the following X-ray crystallographic analysis that the novel isoaurone compound, (II), has the E-configuration. This result clearly indicates that the glycolic acid product, (I), possesses the (2R,3R) [or (2S,3S)] configuration, if the dehydration step leading to the isoaurone (II) occurs by the expected concerted anti-periplanar E2 elimination reaction at (I). In the original paper (Brady et al., 1989) reporting the synthesis of (I) as the result of a benzilic acid rearrangement on 1-(2-hydroxy-4-methoxyphenyl)-3-methoxy-3-phenylpropan-1,2-dione, compound (I) was assigned the (2R,3S)-configuration on the basis of a mechanistic postulate. At the present moment the mechanism of this reaction is being re-evaluated. In the original paper (Brady et al., 1989) the diagram clearly shows that the glycolic acid product had the (2R,3S)-configuration, but it was inadvertently named (2R,3R) in the text. This error was carried over into our subsequent paper (Burke et al., 1997).

The furanone ring of the title compound, (II), which is essentially planar, is fused to a methoxybenzene ring system. Both ring systems are approximately coplanar, the angle between the furanone moiety and the fused benzene ring being 175.7 (1)°. Selected bond lengths and angles in Table 1 show that the benzene ring C4—C9 has a remarkable amount of angle strain arising from the ring fusion. The internal bond angles [C7 115.8 (1), C8 124.7 (1), C9 118.5 (1) and C4 118.9 (1)°] are all somewhat different from 120.0°, whereas the vinylic phenyl ring has internal angles between 119.7 (1) and 120.2 (1)°. In accordance with an earlier nuclear Overhauser effect experiment, the present X-ray experiment shows the large distance of 3.703 (16) Å between H4 and the C12 methyl of the vinylic methoxyl group (Fig. 1). It is also worth observing that the vinylic phenyl group is rotated out of the plane with the benzofuranone moiety by 78.8 (1)°. This had already been predicted using Dreiding molecular models. Some prominent torsion angles are also shown in Table 1.

The molecules in the crystal of (II) are packed together via intermolecular C—H···O interactions and stacking between the benzofuranone ring systems. If we consider the intramolecular hydrogen bond C4—H4···O10 and the intermolecular hydrogen bond C4—H4···O2, then H4 has a bifurcated donor function. With the intermolecular C12—H123···O2 bond the keto oxygen O2 is a bifurcated acceptor. The above mentioned hydrogen bonds form discrete layers along b. The view along the b axis (Fig. 2) shows that these layers are connected along the c direction via another intermolecular hydrogen bond, C11—H112···O6, where the methoxy H atom acts as a donor. Details of the hydrogen bonding system are given in Table 2. Furthermore, stacking of the benzofuranone moieties is also displayed in Fig. 2. The stacking follows the [201] direction; the distance between the centres of gravity of the rings is 3.672 (1) Å.

S2. Experimental

Compound (II) was prepared as follows. A mixture of (2R,3R)-2-hydroxy-2-(2-hydroxy-4-methoxyphenyl)-3-methoxy-3-phenylpropan-1-oic acid, (I) (0.3 g, 0.94 mmol; Brady et al., 1989) and acetic anhydride (10 ml) was heated under reflux for 2 h. The cooled solution was poured into iced water (30 ml). The resulting yellow solid was collected and crystallized from ethanol as yellow-green needles of (II) (yield 0.079 g, 30%; m.p. 435–437 K). Analysis, found: C 72.05, H 5.01%; C₁₇H₁₄O₄ requires: C 72.32, H 5.01%; IR ν_max,KBr, cm^-1: 1762, 1626 and 1587; λ_max, 95% EtOH, nm: 206.1 (ε/dm³mol^-1cm^-1 23, 709), 233.2 (13, 923), 256.6 (11, 895) and 342 (13, 861); ¹H NMR, 270 MHz, CDCl₃, p.p.m.: 3.71 (s, 3H), 3.83 (s, 3H), 6.66 (d, J = 2.2 Hz, 1H), 6.70 (dd, J = 8.2, 2.4 Hz, 1H), 7.41 (m, 2H), 7.52 (m, 3H), and 7.70 (d, J = 8.2 Hz, 1H); ¹³C NMR, 67.80 MHz, CDCl₃, p.p.m.: 55.63, 57.72, 96.63, 103.18, 109.19, 116.82, 123.87, 128.74, 128.99, 130.32, 130.56, 152.56, 159.95, 168.02, and 168.21; mass spectroscopy m/z (E·I.): 282.1 (M+,100), 267.1 (23), 239.1 (50), 211.1 (3) and 105 (50%). Evaporation of the filtrate to half its volume yielded cubes of (αR,βR)-3-acetoxy-6-methoxy-3-[(R)-methoxyphenylmethyl]benzo[b]furan- 2(3H)-one, (III) (yield 0.129 g, 40%; m.p. 409–411 K). Analysis, found: C 66.94, H 5.35%; C₁₉H₁₈O₆ requires: C 66.66, H 5.30%; IR ν_max, KBr, cm^-1: 1821, 1752 and 1635; ¹H NMR, 270 MHz, CDCl₃, p.p.m.: 2.03 (s, 3H), 3.24 (s, 3H), 3.79 (s, 3H), 4.78 (s, 1H), 6.14 (d, 8.2 Hz, 1H), 6.46 (dd, J = 8.2, 2.3 Hz, 1H), 6.71 (d, J = 2.3 Hz, 1H), 7.32 (m, 2H) and 7.42 (m,3H); ¹³C NMR, 67.80 MHz, CDCl₃, p.p.m.: 20.37, 55.55, 57.72, 79.33, 83.93, 97.28, 109.29, 113.70, 126.02, 127.90, 128.51, 128.81, 134.5, 156.30, 162.05, 168.45, and 173.84; mass spectroscopy, m/z (E·I.) 342 (M+,1), 282 (3), 252 (4), 209 (5), 165 (2) and 121 (100%). An alternative synthesis of (II) proceeds as follows. A mixture of 3-benzoyl-6-methoxybenzofuran-2-one, (IV) (0.076 g, 0.284 mmol; Brady, Burke & O'Sullivan, unpublished results), dimethylsulfate (0.1 ml, 1.06 mmol), anhydrous potassium carbonate (3 g, 21.7 mmol) and dry acetone (20 ml) was heated under reflux for 2 h. The cooled mixture was filtered free of inorganic matter and diluted with ice and water. The resulting precipitate crystallized from ethanol as green-yellow needles of (II) (yield 0.05 g, 62%; m.p. 436 K). All the chiral compounds discussed or shown in this paper existed as racemic mixtures; only one member of the enantiomeric pair is mentioned in each case for the sake of convenience.

S3. Refinement

The positions of the H atoms were determined from difference electron density maps and they were refined with isotropic displacement parameters. C—H bond lengths range between 0.960 (15) and 1.062 (15) Å.

Computing details

Data collection: IPDS Software (Stoe & Cie, 1999); cell refinement: IPDS Software; data reduction: IPDS (Stoe & Cie, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1990) and PLUTON (Spek, 1991); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. PLATON (Spek, 1990) displacement ellipsoid plot of (II) at the 50% probability level with the atom-numbering scheme. H atoms are drawn as small spheres of arbitrary radii.
	Fig. 2. PLUTON (Spek, 1991) packing diagram for (II) exhibiting the layered structure along b and the stacking of the layers via centres of symmetry. The hydrogen bonds are shown as dashed lines.

(E)-6-Methoxy-3-(α-methoxybenzylidene)benzo[b]furan-2(3H)-one

Crystal data

C17H14O4	F(000) = 592
Mr = 282.28	Dx = 1.396 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.5235 (8) Å	Cell parameters from 8000 reflections
b = 7.1136 (3) Å	θ = 2.7–30.3°
c = 18.2587 (13) Å	µ = 0.10 mm^−1
β = 100.632 (9)°	T = 173 K
V = 1343.38 (15) Å^3	Plate, green-yellow
Z = 4	0.54 × 0.35 × 0.06 mm

Data collection

STOE IPDS diffractometer	3849 independent reflections
Radiation source: fine-focus sealed tube	2237 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ϕ oscillation scan	θmax = 30.3°, θmin = 2.7°
Absorption correction: numerical (Coppens et al., 1965)	h = −14→14
Tmin = 0.948, Tmax = 0.994	k = 0→9
13623 measured reflections	l = 0→25

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)] = 0.034	Hydrogen site location: difference Fourier map
wR(F^2) = 0.067	All H-atom parameters refined
S = 1.01	w = 1/[σ^2(Fo^2) + (0.02P)^2] where P = (Fo^2 + 2Fc^2)/3
3849 reflections	(Δ/σ)max = 0.001
246 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.19 e Å^−3

Special details

Experimental. see text

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	0.14312 (8)	0.45269 (13)	0.04033 (5)	0.0239 (2)
C2	0.21942 (11)	0.4314 (2)	−0.01451 (7)	0.0217 (3)
C3	0.24854 (11)	0.23111 (18)	−0.01970 (6)	0.0181 (2)
O2	0.24959 (9)	0.56855 (14)	−0.04549 (5)	0.0299 (2)
O6	−0.05484 (8)	−0.00156 (14)	0.18274 (5)	0.0302 (2)
C4	0.16315 (11)	−0.05095 (19)	0.05131 (6)	0.0196 (3)
C5	0.08338 (11)	−0.09014 (19)	0.10206 (6)	0.0211 (3)
C6	0.02358 (11)	0.0556 (2)	0.13461 (6)	0.0220 (3)
C7	0.04185 (11)	0.2424 (2)	0.11771 (7)	0.0220 (3)
C8	0.12091 (11)	0.27452 (19)	0.06667 (6)	0.0199 (3)
C9	0.18271 (11)	0.13518 (18)	0.03340 (6)	0.0182 (3)
C10	0.32742 (11)	0.16059 (18)	−0.06380 (6)	0.0188 (3)
O10	0.35617 (8)	−0.02281 (13)	−0.05469 (5)	0.0258 (2)
C11	−0.11999 (15)	0.1424 (3)	0.21584 (9)	0.0364 (4)
C12	0.43437 (14)	−0.1146 (2)	−0.10131 (8)	0.0260 (3)
C13	0.38169 (11)	0.27525 (18)	−0.11886 (6)	0.0187 (3)
C14	0.30141 (12)	0.3359 (2)	−0.18365 (7)	0.0247 (3)
C15	0.35007 (13)	0.4492 (2)	−0.23387 (7)	0.0285 (3)
C16	0.47850 (13)	0.5019 (2)	−0.21936 (7)	0.0273 (3)
C17	0.55936 (13)	0.4398 (2)	−0.15550 (7)	0.0282 (3)
C18	0.51135 (12)	0.3256 (2)	−0.10526 (7)	0.0242 (3)
H4	0.2027 (12)	−0.155 (2)	0.0279 (7)	0.026 (4)*
H5	0.0637 (12)	−0.231 (2)	0.1161 (7)	0.029 (4)*
H7	−0.0007 (12)	0.346 (2)	0.1369 (7)	0.028 (4)*
H111	−0.1721 (14)	0.071 (2)	0.2490 (8)	0.047 (4)*
H112	−0.0558 (15)	0.226 (3)	0.2494 (9)	0.052 (5)*
H113	−0.1778 (15)	0.217 (2)	0.1764 (9)	0.047 (5)*
H121	0.3967 (13)	−0.089 (2)	−0.1539 (8)	0.035 (4)*
H122	0.5262 (14)	−0.069 (2)	−0.0883 (8)	0.035 (4)*
H123	0.4284 (14)	−0.253 (3)	−0.0926 (8)	0.044 (4)*
H14	0.2063 (14)	0.305 (2)	−0.1933 (8)	0.040 (4)*
H15	0.2907 (13)	0.492 (2)	−0.2812 (8)	0.034 (4)*
H16	0.5114 (13)	0.586 (2)	−0.2540 (8)	0.032 (4)*
H17	0.6518 (14)	0.481 (2)	−0.1449 (8)	0.042 (4)*
H18	0.5673 (12)	0.286 (2)	−0.0575 (8)	0.034 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0281 (4)	0.0150 (5)	0.0315 (5)	0.0014 (4)	0.0128 (4)	−0.0017 (4)
C2	0.0199 (6)	0.0207 (7)	0.0249 (6)	0.0000 (5)	0.0049 (5)	−0.0001 (5)
C3	0.0194 (5)	0.0153 (7)	0.0196 (6)	−0.0002 (5)	0.0033 (4)	0.0007 (5)
O2	0.0376 (5)	0.0172 (5)	0.0383 (5)	−0.0003 (4)	0.0157 (4)	0.0028 (4)
O6	0.0339 (5)	0.0310 (6)	0.0308 (5)	0.0004 (4)	0.0189 (4)	0.0010 (4)
C4	0.0228 (6)	0.0174 (7)	0.0186 (6)	0.0025 (5)	0.0042 (5)	−0.0014 (5)
C5	0.0236 (6)	0.0194 (8)	0.0205 (6)	−0.0002 (5)	0.0047 (5)	0.0014 (5)
C6	0.0200 (6)	0.0283 (8)	0.0183 (6)	−0.0011 (6)	0.0054 (5)	−0.0003 (5)
C7	0.0214 (6)	0.0220 (8)	0.0237 (6)	0.0017 (6)	0.0068 (5)	−0.0052 (5)
C8	0.0200 (6)	0.0163 (7)	0.0226 (6)	−0.0005 (5)	0.0019 (5)	−0.0009 (5)
C9	0.0182 (5)	0.0181 (7)	0.0180 (6)	0.0009 (5)	0.0028 (5)	−0.0007 (5)
C10	0.0215 (6)	0.0150 (7)	0.0197 (6)	−0.0003 (5)	0.0031 (5)	0.0006 (5)
O10	0.0375 (5)	0.0169 (5)	0.0281 (5)	0.0067 (4)	0.0192 (4)	0.0034 (4)
C11	0.0372 (8)	0.0409 (10)	0.0374 (8)	−0.0043 (8)	0.0230 (7)	−0.0102 (8)
C12	0.0338 (7)	0.0206 (9)	0.0272 (7)	0.0058 (6)	0.0151 (6)	−0.0008 (6)
C13	0.0232 (6)	0.0138 (7)	0.0202 (6)	0.0016 (5)	0.0070 (5)	−0.0002 (5)
C14	0.0250 (6)	0.0249 (8)	0.0246 (6)	0.0031 (6)	0.0055 (5)	0.0026 (5)
C15	0.0362 (7)	0.0275 (8)	0.0224 (6)	0.0063 (6)	0.0070 (6)	0.0053 (6)
C16	0.0424 (8)	0.0178 (8)	0.0262 (6)	−0.0018 (6)	0.0181 (6)	−0.0001 (6)
C17	0.0283 (7)	0.0287 (8)	0.0300 (7)	−0.0073 (6)	0.0119 (6)	−0.0029 (6)
C18	0.0242 (6)	0.0269 (8)	0.0214 (6)	−0.0014 (6)	0.0040 (5)	0.0005 (5)

Geometric parameters (Å, º)

O1—C8	1.3905 (16)	O10—C12	1.4447 (15)
O1—C2	1.4024 (14)	C11—H111	1.023 (16)
C2—O2	1.1993 (15)	C11—H112	1.015 (17)
C2—C3	1.4644 (18)	C11—H113	1.005 (17)
C3—C10	1.3550 (16)	C12—H121	0.987 (14)
C3—C9	1.4605 (17)	C12—H122	1.005 (14)
O6—C6	1.3733 (14)	C12—H123	1.000 (18)
O6—C11	1.4273 (18)	C13—C18	1.3881 (16)
C4—C9	1.3883 (18)	C13—C14	1.3893 (17)
C4—C5	1.3885 (16)	C14—C15	1.3878 (19)
C4—H4	0.985 (14)	C14—H14	1.007 (14)
C5—C6	1.4007 (18)	C15—C16	1.3803 (19)
C5—H5	1.062 (15)	C15—H15	1.017 (14)
C6—C7	1.3860 (19)	C16—C17	1.3829 (19)
C7—C8	1.3781 (16)	C16—H16	0.980 (15)
C7—H7	0.960 (15)	C17—C18	1.3885 (18)
C8—C9	1.3857 (17)	C17—H17	0.999 (14)
C10—O10	1.3426 (15)	C18—H18	0.998 (14)
C10—C13	1.4879 (17)
C8—O1—C2	107.67 (9)	O6—C11—H111	104.3 (10)
O2—C2—O1	119.04 (11)	O6—C11—H112	110.9 (9)
O2—C2—C3	133.17 (11)	H111—C11—H112	107.6 (12)
O1—C2—C3	107.77 (10)	O6—C11—H113	110.6 (9)
C10—C3—C9	129.73 (12)	H111—C11—H113	111.5 (12)
C10—C3—C2	123.86 (11)	H112—C11—H113	111.7 (14)
C9—C3—C2	106.33 (10)	O10—C12—H121	108.7 (8)
C6—O6—C11	116.80 (11)	O10—C12—H122	110.0 (8)
C9—C4—C5	118.87 (11)	H121—C12—H122	111.5 (11)
C9—C4—H4	121.5 (8)	O10—C12—H123	107.0 (8)
C5—C4—H4	119.6 (8)	H121—C12—H123	108.1 (12)
C4—C5—C6	120.59 (12)	H122—C12—H123	111.4 (12)
C4—C5—H5	121.3 (7)	C18—C13—C14	119.70 (11)
C6—C5—H5	118.1 (7)	C18—C13—C10	120.52 (11)
O6—C6—C7	123.42 (11)	C14—C13—C10	119.77 (10)
O6—C6—C5	115.00 (12)	C15—C14—C13	120.15 (12)
C7—C6—C5	121.57 (11)	C15—C14—H14	119.0 (9)
C8—C7—C6	115.81 (11)	C13—C14—H14	120.7 (8)
C8—C7—H7	120.1 (8)	C16—C15—C14	119.90 (12)
C6—C7—H7	124.0 (8)	C16—C15—H15	120.5 (8)
C7—C8—C9	124.66 (12)	C14—C15—H15	119.6 (8)
C7—C8—O1	123.08 (11)	C15—C16—C17	120.24 (12)
C9—C8—O1	112.21 (10)	C15—C16—H16	119.5 (8)
C8—C9—C4	118.49 (11)	C17—C16—H16	120.2 (8)
C8—C9—C3	105.97 (11)	C16—C17—C18	120.10 (12)
C4—C9—C3	135.32 (11)	C16—C17—H17	119.7 (9)
O10—C10—C3	115.77 (11)	C18—C17—H17	120.1 (9)
O10—C10—C13	120.71 (10)	C13—C18—C17	119.89 (12)
C3—C10—C13	123.52 (12)	C13—C18—H18	119.1 (8)
C10—O10—C12	120.41 (10)	C17—C18—H18	120.9 (8)
C8—O1—C2—O2	179.39 (11)	C10—C3—C9—C8	176.49 (12)
C8—O1—C2—C3	−2.05 (12)	C2—C3—C9—C8	−0.32 (13)
O2—C2—C3—C10	2.7 (2)	C10—C3—C9—C4	−9.2 (2)
O1—C2—C3—C10	−175.58 (10)	C2—C3—C9—C4	174.00 (13)
O2—C2—C3—C9	179.74 (13)	C9—C3—C10—O10	−4.39 (18)
O1—C2—C3—C9	1.47 (13)	C2—C3—C10—O10	171.92 (11)
C9—C4—C5—C6	0.03 (17)	C9—C3—C10—C13	176.25 (11)
C11—O6—C6—C7	0.32 (17)	C2—C3—C10—C13	−7.45 (18)
C11—O6—C6—C5	−178.61 (12)	C3—C10—O10—C12	177.00 (11)
C4—C5—C6—O6	178.80 (11)	C13—C10—O10—C12	−3.62 (17)
C4—C5—C6—C7	−0.16 (18)	O10—C10—C13—C18	−72.54 (16)
O6—C6—C7—C8	−178.22 (11)	C3—C10—C13—C18	106.79 (14)
C5—C6—C7—C8	0.65 (17)	O10—C10—C13—C14	108.86 (14)
C6—C7—C8—C9	−1.09 (18)	C3—C10—C13—C14	−71.80 (17)
C6—C7—C8—O1	176.08 (11)	C18—C13—C14—C15	−1.2 (2)
C2—O1—C8—C7	−175.54 (11)	C10—C13—C14—C15	177.39 (13)
C2—O1—C8—C9	1.94 (12)	C13—C14—C15—C16	0.0 (2)
C7—C8—C9—C4	1.00 (18)	C14—C15—C16—C17	1.0 (2)
O1—C8—C9—C4	−176.44 (10)	C15—C16—C17—C18	−0.6 (2)
C7—C8—C9—C3	176.45 (11)	C14—C13—C18—C17	1.6 (2)
O1—C8—C9—C3	−0.98 (13)	C10—C13—C18—C17	−177.04 (12)
C5—C4—C9—C8	−0.42 (17)	C16—C17—C18—C13	−0.6 (2)
C5—C4—C9—C3	−174.20 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O2^i	0.985 (14)	2.480 (14)	3.4454 (16)	166.6 (10)
C4—H4···O10	0.985 (14)	2.582 (13)	3.0598 (15)	109.9 (10)
C11—H112···O6^ii	1.016 (18)	2.47 (2)	3.460 (2)	163.7 (15)
C12—H123···O2^i	1.00 (2)	2.547 (17)	3.2606 (18)	128.0 (12)

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