Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di-acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis-(pent-4-ynoate).

In the structures of the two title coumarin derivatives, C14H12O6, (1), and C20H16O6, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by π-π stacking involving the coumarin rings and weak C-H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R 2 (2)(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol-ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π-π stacking.

Chemical context

Coumarins and their derivatives have wide applications in a number of diverse areas. They are used in the pharmaceutical industry as precursor reagents in the synthesis of a number of synthetic anti­coagulant pharmaceuticals (Bairagi et al., 2012 ▸), the most notable being warfarin (Holbrook et al., 2005 ▸). Modified coumarins are a type of vitamin K antagonist (Marongiu & Barcellona, 2015 ▸).

In another important application, coumarin dyes are extensively used as gain media in blue–green tunable organic dye lasers (Schäfer, 1990 ▸; Duarte & Hillman, 1990 ▸; Duarte, 2003 ▸). Coumarin tetra­methyl laser dyes offer wide tunability and high laser gain (Chen et al., 1988 ▸; Duarte et al., 2006 ▸), and they are also used as the active medium in coherent OLED emitters (Duarte et al., 2005 ▸).

4-Methyl coumarin derivatives have previously been used as acetyl-group donors for post-translational modification of proteins via an acet­yl–CoA independent mechanism (Raj, Singh et al., 2005 ▸; Raj, Kumari et al., 2006 ▸). Calreticulin-mediated acetyl­ation of gluta­thione-S-transferase (GST) using substrate 7,8-diacety­oxy-4-methyl coumarin, DAMC (1) (systematic name: 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate) has been shown to inhibit GST activity in a spectroscopic assay (Raj, Singh et al., 2005 ▸). The crystal structure of the related compound 7,8-dihy­droxy-4-methyl­coumarin (Kurosaki et al., 2003 ▸) has been reported. Pentynoyl probes have been used as chemical reporters to monitor protein acetyl­ation (Bateman et al., 2013 ▸; Yang et al., 2010 ▸). For background to bio-orthogonal reactions using alkyne–azide cyclo­addition, see Sletten & Bertozzi (2011 ▸) and Yang & Hang (2011 ▸).

We have synthesized a new coumarin derivative, 7,8-dipentyno­yloxy-4-methyl coumarin, DPeMC (2) [systematic name: 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate)] as a chemical reporter of calreticulin’s acyl­transferase capabilities (Singh et al., 2011 ▸). As part of this work, the crystal structures of both coumarin derivatives are presented in this article.

Structural commentary

This paper reports the structures of two derivatives of coumarin (systematic name; 2H-chromen-2-one), C14H12O6 (1) and C20H16O6 (2), which are to be used as chemical reporters of calreticulin’s acyl­transferase capabilities. These two compounds will be first discussed individually and then compared.

In the structure of (1) (Fig. 1 ▸), the coumarin ring is almost planar (r.m.s. deviation of fitted atoms = 0.0063 Å) with O2 in the plane [deviation of 0.0048 (9) Å]. Both acetate substituents are significantly rotated out of this plane to minimize steric repulsions [dihedral angle of 66.19 (7)° to the coumarin ring for O3, O4, and C11, and 79.4 (3)° for O5, C13 O6A]. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17). The metrical parameters of both the coumarin ring and acetate substituents are in the normal ranges.

Figure 1

Diagram of the structure and numbering scheme for (1), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.

In (2) (Fig. 2 ▸), the C≡C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). The coumarin ring is almost planar (r.m.s. deviation of fitted atoms = 0.0305 Å) with O2 significantly out of this plane [0.144 (2) Å] but O3 in the plane [0.063 (2) Å]. One of the pent-4-ynoate substituents is in an extended conformation (O5 to C21) while the other is in a bent conformation about C13. This can be seen from a consideration of the O3—C12—C13—C14 torsion angle of −46.3 (2)° compared to the equivalent torsion angle O5—C17—C18—C19 of 176.16 (12)°. The planar parts of both pent-4-ynoate substituents deviate from the coumarin plane but by different amounts [40.90 (15)° for O3, O4 and C12 compared to 74.07 (10)° for O5, O6 and C17]. The metrical parameters of both the coumarin ring and pent-4-ynoate substituents are in the normal ranges including the C≡C triple bonds [C15A≡C16A = 1.186 (9), C15B≡C16B = 1.169 (11) and C20≡C21 = 1.177 (3) Å].

Figure 2

Diagram of the structure and numbering scheme for (2), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.

Supra­molecular features

The packing of (1) is dominated by π–π stacking involving the coumarin rings [centroid–centroid distance of 3.6640 (5) Å, slippage of 1.422 Å, symmetry code 1 − x, 1 − y, 1 − z]. This can be observed in Fig. 3 ▸. In addition, there are weak C—H⋯O contacts (Table 1 ▸) involving C13 and O6A(x, 1 + y, z) as well as C6 and O2(x − 1, 1 + y, z), C15A and O2 (1 − x, −y, 2 − z) which link the parallel stacks in the [101] direction.

Figure 3

Packing diagram for (1), viewed along the c axis, showing the parallel coumarin rings. C—H⋯O secondary inter­actions are drawn with dashed lines.

Table 1

Hydrogen-bond geometry (Å, °) for (1)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6A⋯O2i	0.95	2.65	3.3465 (17)	130
C13—H13A⋯O6A ii	0.98	2.48	3.451 (5)	173
C15A—H15B⋯O2iii	0.98	2.52	3.401 (8)	150

Symmetry codes: (i) ; (ii) ; (iii) .

In contrast to (1), for (2) the packing (Fig. 4 ▸) is dominated by (24) hydrogen bonds (Table 2 ▸) involving the acidic sp H atom and O2 which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π–π stacking in contrast to (1).

Figure 4

Packing diagram for (2), viewed along the a axis. (24) hydrogen bonds involving the acidic sp H and O2 atoms link the mol­ecules into centrosymmetric dimers. C—H⋯O secondary inter­actions are drawn with dashed lines.

Table 2

Hydrogen-bond geometry (Å, °) for (2)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13—H13B⋯O4i	0.99	2.43	3.244 (2)	139
C18—H18A⋯O6i	0.99	2.51	3.482 (2)	167

Symmetry code: (i) .

Database survey

Our group has reported a number of related structures (Jasinski & Paight, 1994 ▸, 1995 ▸; Jasinski & Woudenberg, 1994 ▸, 1995 ▸; Jasinski & Li, 2002 ▸; Jasinski et al., 1998 ▸, 2003 ▸; Butcher et al., 2007 ▸).

Synthesis and crystallization

7,8-Diacet­oxy-4-methyl­coumarin (1). 4-Methyl-2-oxo-2H-chromene-7,8-diyl di­acetate (DAMC) was synthesized using a previously reported procedure (Jalal et al., 2012 ▸).

7,8-Dipentyno­yloxy-4-methyl­coumarin (2). 0.5 mmol 7,8-dihy­droxy-4-methyl coumarin, DHMC [systematic name: 7,8-dihy­droxy-4-methyl-2H-chromen-2-one], 2.5 equivalents pentynoic anhydride (Malkoch et al., 2005 ▸) and catalytic 4-di­methyl­amino­pyridine (DMAP) was stirred for 24 h at room temperature in anhydrous THF (2 mL). Ice-cold water (25 mL) was added to the reaction flask, and the filtered crude product was washed with hexa­nes followed by recrystallization from ethanol to obtain small brown crystals of 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate).

Spectroscopic analysis: 1H NMR (400 MHz, CDCl3): δ 7.51–7.49 (1H, d), δ 7.20–7.17 (1H, d), δ 6.29 (1H, s), δ 3.01–3.08 (2H, m, HC≡C), δ 2.89–2.84 (2H, t, C≡C—CH2), δ 2.61–2.70 (4H, m, OOC—CH2), δ 2.44 (3H, s, CH3), δ 2.09–2.11 (2H, C≡C-–CH2).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. For (1), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.98 Å with U(H) = 1.5U eq(C) for methyl H atoms and = 1.2U(C) for other H atoms. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17).

Table 3

Experimental details

	(1)	(2)
Crystal data
Chemical formula	C14H12O6	C20H16O6
M r	276.24	352.33
Crystal system, space group	Triclinic, P	Monoclinic, P21/n
Temperature (K)	173	200
a, b, c (Å)	7.3722 (10), 8.7235 (7), 11.7032 (15)	5.2785 (3), 16.3785 (8), 20.0502 (11)
α, β, γ (°)	69.263 (10), 87.519 (11), 69.113 (10)	90, 95.992 (2), 90
V (Å3)	654.66 (14)	1723.95 (16)
Z	2	4
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	0.11	0.10
Crystal size (mm)	0.33 × 0.26 × 0.11	0.55 × 0.14 × 0.11
Data collection
Diffractometer	Agilent Xcalibur Eos Gemini	Bruker Quest
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2014 ▸)	Multi-scan (SADABS; Sheldrick, 1996 ▸)
T min, T max	0.883, 1.000	0.658, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	7360, 4296, 3087	24358, 5276, 3859
R int	0.036	0.035
(sin θ/λ)max (Å−1)	0.759	0.716
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.055, 0.156, 1.04	0.057, 0.142, 1.07
No. of reflections	4296	5276
No. of parameters	192	255
No. of restraints	13	13
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.36, −0.24	0.37, −0.21

Computer programs: CrysAlis PRO (Agilent, 2014 ▸), APEX2 (Bruker, 2005 ▸), SAINT (Bruker, 2002 ▸), SHELXT (Sheldrick, 2015a ▸), SHELXL2014 (Sheldrick, 2015b ▸) and SHELXTL (Sheldrick, 2008 ▸).

In the refinement for (2), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.99 Å with U iso(H) = 1.5U eq(C) for methyl H atoms and = 1.2U(C) for other H atoms. The C≡C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2).

Crystal structure: contains datablock(s) 1, 2. DOI: 10.1107/S2056989016005892/hg5471sup1.cif

Structure factors: contains datablock(s) 1. DOI: 10.1107/S2056989016005892/hg54711sup2.hkl

Structure factors: contains datablock(s) 2. DOI: 10.1107/S2056989016005892/hg54712sup3.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989016005892/hg54711sup4.cml

CCDC references: 1473151, 1473150

Additional supporting information: crystallographic information; 3D view; checkCIF report

C14H12O6	Z = 2
Mr = 276.24	F(000) = 288
Triclinic, P1	Dx = 1.401 Mg m−3
a = 7.3722 (10) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.7235 (7) Å	Cell parameters from 1905 reflections
c = 11.7032 (15) Å	θ = 4.4–32.8°
α = 69.263 (10)°	µ = 0.11 mm−1
β = 87.519 (11)°	T = 173 K
γ = 69.113 (10)°	The symmetry employed for this shelxl refinement is uniquely defined by the following loop, which should always be used as a source of symmetry information in preference to the above space-group names. They are only intended as comments., colorless
V = 654.66 (14) Å3	0.33 × 0.26 × 0.11 mm

Agilent Xcalibur Eos Gemini diffractometer	4296 independent reflections
Radiation source: Enhance (Mo) X-ray Source	3087 reflections with I > 2σ(I)
Detector resolution: 16.0416 pixels mm-1	Rint = 0.036
ω scans	θmax = 32.7°, θmin = 3.2°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −11→8
Tmin = 0.883, Tmax = 1.000	k = −13→12
7360 measured reflections	l = −16→17

Refinement on F2	13 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.055	H-atom parameters constrained
wR(F2) = 0.156	w = 1/[σ2(Fo2) + (0.0738P)2 + 0.0282P] where P = (Fo2 + 2Fc2)/3
S = 1.04	(Δ/σ)max < 0.001
4296 reflections	Δρmax = 0.36 e Å−3
192 parameters	Δρmin = −0.24 e Å−3

Experimental. Absorption correction: CrysAlisPro (Agilent Technologies, 2014) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	0.48459 (13)	0.24436 (11)	0.69118 (8)	0.0225 (2)
O2	0.67011 (16)	0.00141 (12)	0.66239 (10)	0.0336 (3)
O3	0.09094 (15)	0.73883 (12)	0.78120 (9)	0.0264 (2)
O4	0.20400 (17)	0.95648 (13)	0.68569 (10)	0.0332 (3)
O5	0.38600 (14)	0.41942 (12)	0.84842 (8)	0.0238 (2)
C2	0.54690 (19)	0.14688 (16)	0.61566 (13)	0.0234 (3)
C3	0.4606 (2)	0.22921 (16)	0.49018 (12)	0.0235 (3)
H3A	0.5012	0.1646	0.4372	0.028*
C4	0.32496 (19)	0.39359 (16)	0.44454 (12)	0.0203 (2)
C11	0.2429 (2)	0.47678 (18)	0.31289 (12)	0.0267 (3)
H11A	0.2925	0.3903	0.2729	0.040*
H11B	0.2823	0.5775	0.2711	0.040*
H11C	0.1003	0.5170	0.3085	0.040*
C10	0.26109 (18)	0.49190 (15)	0.52589 (11)	0.0183 (2)
C5	0.11893 (18)	0.66244 (15)	0.49057 (12)	0.0209 (3)
H5A	0.0596	0.7197	0.4086	0.025*
C6	0.06342 (19)	0.74874 (15)	0.57236 (12)	0.0225 (3)
H6A	−0.0339	0.8636	0.5473	0.027*
C7	0.15204 (19)	0.66502 (15)	0.69197 (12)	0.0207 (2)
C8	0.29286 (18)	0.49730 (15)	0.72996 (11)	0.0193 (2)
C9	0.34563 (17)	0.41057 (14)	0.64741 (12)	0.0183 (2)
C12	0.1158 (2)	0.89364 (16)	0.76502 (13)	0.0244 (3)
C13	0.0176 (3)	0.9662 (2)	0.85859 (16)	0.0368 (4)
H13A	0.0693	1.0528	0.8641	0.055*
H13B	0.0421	0.8704	0.9386	0.055*
H13C	−0.1231	1.0232	0.8347	0.055*
C14	0.3169 (3)	0.3042 (2)	0.93265 (14)	0.0376 (4)
O6A	0.1945 (8)	0.2587 (9)	0.9046 (3)	0.0509 (11)	0.755 (17)
C15A	0.4350 (12)	0.2219 (9)	1.0560 (7)	0.0572 (13)	0.755 (17)
H15A	0.5502	0.1208	1.0568	0.086*	0.755 (17)
H15B	0.3550	0.1827	1.1207	0.086*	0.755 (17)
H15C	0.4764	0.3090	1.0706	0.086*	0.755 (17)
O6B	0.150 (2)	0.3148 (19)	0.9106 (11)	0.0509 (11)	0.245 (17)
C15B	0.406 (4)	0.265 (3)	1.051 (2)	0.0572 (13)	0.245 (17)
H15D	0.3343	0.3584	1.0818	0.086*	0.245 (17)
H15E	0.5415	0.2586	1.0435	0.086*	0.245 (17)
H15F	0.4039	0.1523	1.1073	0.086*	0.245 (17)

	U11	U22	U33	U12	U13	U23
O1	0.0247 (5)	0.0181 (4)	0.0211 (5)	−0.0030 (3)	−0.0014 (4)	−0.0075 (3)
O2	0.0349 (6)	0.0229 (5)	0.0345 (6)	−0.0005 (4)	0.0013 (5)	−0.0107 (4)
O3	0.0366 (5)	0.0242 (4)	0.0236 (5)	−0.0127 (4)	0.0108 (4)	−0.0137 (4)
O4	0.0434 (6)	0.0334 (5)	0.0314 (6)	−0.0202 (5)	0.0118 (5)	−0.0162 (4)
O5	0.0286 (5)	0.0265 (4)	0.0171 (4)	−0.0115 (4)	−0.0004 (4)	−0.0069 (3)
C2	0.0247 (6)	0.0201 (5)	0.0263 (7)	−0.0074 (5)	0.0053 (5)	−0.0105 (5)
C3	0.0276 (6)	0.0242 (6)	0.0239 (7)	−0.0109 (5)	0.0064 (5)	−0.0135 (5)
C4	0.0227 (6)	0.0237 (5)	0.0196 (6)	−0.0125 (5)	0.0048 (5)	−0.0099 (5)
C11	0.0313 (7)	0.0320 (7)	0.0204 (7)	−0.0131 (6)	0.0023 (5)	−0.0118 (5)
C10	0.0194 (6)	0.0198 (5)	0.0178 (6)	−0.0091 (4)	0.0025 (4)	−0.0072 (4)
C5	0.0218 (6)	0.0207 (5)	0.0189 (6)	−0.0080 (4)	0.0007 (5)	−0.0052 (4)
C6	0.0232 (6)	0.0183 (5)	0.0236 (7)	−0.0056 (4)	0.0031 (5)	−0.0070 (5)
C7	0.0242 (6)	0.0207 (5)	0.0211 (6)	−0.0100 (5)	0.0070 (5)	−0.0109 (5)
C8	0.0217 (6)	0.0206 (5)	0.0163 (6)	−0.0092 (4)	0.0009 (4)	−0.0058 (4)
C9	0.0184 (5)	0.0157 (5)	0.0207 (6)	−0.0060 (4)	0.0016 (4)	−0.0066 (4)
C12	0.0278 (6)	0.0237 (6)	0.0240 (7)	−0.0082 (5)	0.0013 (5)	−0.0122 (5)
C13	0.0480 (9)	0.0391 (8)	0.0367 (9)	−0.0195 (7)	0.0147 (7)	−0.0266 (7)
C14	0.0538 (10)	0.0411 (8)	0.0212 (7)	−0.0277 (7)	0.0018 (7)	−0.0045 (6)
O6A	0.076 (2)	0.061 (2)	0.0308 (8)	−0.053 (2)	0.0009 (11)	−0.0047 (13)
C15A	0.088 (3)	0.055 (3)	0.0236 (12)	−0.038 (3)	−0.0136 (16)	0.006 (2)
O6B	0.076 (2)	0.061 (2)	0.0308 (8)	−0.053 (2)	0.0009 (11)	−0.0047 (13)
C15B	0.088 (3)	0.055 (3)	0.0236 (12)	−0.038 (3)	−0.0136 (16)	0.006 (2)

O1—C9	1.3691 (14)	C5—H5A	0.9500
O1—C2	1.3906 (15)	C6—C7	1.3910 (19)
O2—C2	1.2100 (16)	C6—H6A	0.9500
O3—C12	1.3731 (15)	C7—C8	1.3829 (17)
O3—C7	1.3916 (15)	C8—C9	1.3901 (17)
O4—C12	1.1945 (17)	C12—C13	1.4898 (19)
O5—C14	1.3641 (17)	C13—H13A	0.9800
O5—C8	1.3921 (15)	C13—H13B	0.9800
C2—C3	1.4440 (19)	C13—H13C	0.9800
C3—C4	1.3502 (18)	C14—O6A	1.205 (4)
C3—H3A	0.9500	C14—O6B	1.234 (14)
C4—C10	1.4544 (17)	C14—C15B	1.43 (2)
C4—C11	1.4973 (19)	C14—C15A	1.512 (7)
C11—H11A	0.9800	C15A—H15A	0.9800
C11—H11B	0.9800	C15A—H15B	0.9800
C11—H11C	0.9800	C15A—H15C	0.9800
C10—C9	1.4005 (18)	C15B—H15D	0.9800
C10—C5	1.4045 (16)	C15B—H15E	0.9800
C5—C6	1.3810 (17)	C15B—H15F	0.9800
C9—O1—C2	120.75 (10)	C9—C8—O5	120.50 (11)
C12—O3—C7	117.51 (10)	O1—C9—C8	116.45 (11)
C14—O5—C8	116.43 (11)	O1—C9—C10	122.58 (11)
O2—C2—O1	116.03 (12)	C8—C9—C10	120.96 (11)
O2—C2—C3	126.76 (13)	O4—C12—O3	122.90 (12)
O1—C2—C3	117.20 (11)	O4—C12—C13	126.98 (13)
C4—C3—C2	123.15 (12)	O3—C12—C13	110.12 (12)
C4—C3—H3A	118.4	C12—C13—H13A	109.5
C2—C3—H3A	118.4	C12—C13—H13B	109.5
C3—C4—C10	118.48 (12)	H13A—C13—H13B	109.5
C3—C4—C11	121.68 (12)	C12—C13—H13C	109.5
C10—C4—C11	119.83 (11)	H13A—C13—H13C	109.5
C4—C11—H11A	109.5	H13B—C13—H13C	109.5
C4—C11—H11B	109.5	O6A—C14—O5	122.2 (2)
H11A—C11—H11B	109.5	O6B—C14—O5	117.7 (6)
C4—C11—H11C	109.5	O6B—C14—C15B	125.8 (15)
H11A—C11—H11C	109.5	O5—C14—C15B	107.3 (11)
H11B—C11—H11C	109.5	O6A—C14—C15A	125.4 (4)
C9—C10—C5	118.01 (11)	O5—C14—C15A	111.6 (3)
C9—C10—C4	117.84 (11)	C14—C15A—H15A	109.5
C5—C10—C4	124.15 (12)	C14—C15A—H15B	109.5
C6—C5—C10	121.47 (12)	H15A—C15A—H15B	109.5
C6—C5—H5A	119.3	C14—C15A—H15C	109.5
C10—C5—H5A	119.3	H15A—C15A—H15C	109.5
C5—C6—C7	119.04 (11)	H15B—C15A—H15C	109.5
C5—C6—H6A	120.5	C14—C15B—H15D	109.5
C7—C6—H6A	120.5	C14—C15B—H15E	109.5
C8—C7—C6	121.09 (11)	H15D—C15B—H15E	109.5
C8—C7—O3	117.00 (11)	C14—C15B—H15F	109.5
C6—C7—O3	121.65 (11)	H15D—C15B—H15F	109.5
C7—C8—C9	119.41 (11)	H15E—C15B—H15F	109.5
C7—C8—O5	120.05 (11)
C9—O1—C2—O2	180.00 (11)	O3—C7—C8—O5	−8.72 (17)
C9—O1—C2—C3	0.67 (17)	C14—O5—C8—C7	98.60 (15)
O2—C2—C3—C4	−179.19 (13)	C14—O5—C8—C9	−83.97 (15)
O1—C2—C3—C4	0.07 (19)	C2—O1—C9—C8	179.93 (11)
C2—C3—C4—C10	−0.66 (19)	C2—O1—C9—C10	−0.79 (17)
C2—C3—C4—C11	178.16 (12)	C7—C8—C9—O1	−179.44 (10)
C3—C4—C10—C9	0.54 (17)	O5—C8—C9—O1	3.11 (17)
C11—C4—C10—C9	−178.31 (11)	C7—C8—C9—C10	1.28 (18)
C3—C4—C10—C5	−178.89 (11)	O5—C8—C9—C10	−176.18 (10)
C11—C4—C10—C5	2.27 (19)	C5—C10—C9—O1	179.64 (10)
C9—C10—C5—C6	0.16 (18)	C4—C10—C9—O1	0.18 (18)
C4—C10—C5—C6	179.58 (11)	C5—C10—C9—C8	−1.12 (18)
C10—C5—C6—C7	0.63 (18)	C4—C10—C9—C8	179.42 (11)
C5—C6—C7—C8	−0.48 (19)	C7—O3—C12—O4	−7.8 (2)
C5—C6—C7—O3	−174.49 (11)	C7—O3—C12—C13	171.97 (12)
C12—O3—C7—C8	120.51 (13)	C8—O5—C14—O6A	6.8 (5)
C12—O3—C7—C6	−65.25 (16)	C8—O5—C14—O6B	−20.6 (8)
C6—C7—C8—C9	−0.46 (18)	C8—O5—C14—C15B	−169.5 (13)
O3—C7—C8—C9	173.82 (11)	C8—O5—C14—C15A	177.4 (4)
C6—C7—C8—O5	177.00 (11)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6A···O2i	0.95	2.65	3.3465 (17)	130
C13—H13A···O6Aii	0.98	2.48	3.451 (5)	173
C15A—H15B···O2iii	0.98	2.52	3.401 (8)	150

C20H16O6	F(000) = 736
Mr = 352.33	Dx = 1.357 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 5.2785 (3) Å	Cell parameters from 9562 reflections
b = 16.3785 (8) Å	θ = 2.5–30.4°
c = 20.0502 (11) Å	µ = 0.10 mm−1
β = 95.992 (2)°	T = 200 K
V = 1723.95 (16) Å3	Rod, colourless
Z = 4	0.55 × 0.14 × 0.11 mm

Bruker Quest diffractometer	3859 reflections with I > 2σ(I)
ω scans	Rint = 0.035
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	θmax = 30.6°, θmin = 2.5°
Tmin = 0.658, Tmax = 0.746	h = −7→6
24358 measured reflections	k = −23→23
5276 independent reflections	l = −28→28

Refinement on F2	13 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.057	H-atom parameters constrained
wR(F2) = 0.142	w = 1/[σ2(Fo2) + (0.0483P)2 + 1.0298P] where P = (Fo2 + 2Fc2)/3
S = 1.07	(Δ/σ)max < 0.001
5276 reflections	Δρmax = 0.37 e Å−3
255 parameters	Δρmin = −0.21 e Å−3

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	0.4888 (2)	0.14589 (6)	0.70580 (6)	0.0315 (3)
O2	0.7381 (3)	0.03765 (8)	0.70909 (7)	0.0482 (4)
O3	−0.0447 (2)	0.37392 (7)	0.67567 (6)	0.0326 (3)
O4	0.1091 (2)	0.50086 (8)	0.66067 (7)	0.0416 (3)
O5	0.0579 (2)	0.21864 (7)	0.64977 (5)	0.0278 (2)
O6	0.3186 (2)	0.22167 (8)	0.56756 (6)	0.0384 (3)
C2	0.7046 (3)	0.10414 (10)	0.73219 (8)	0.0329 (3)
C3	0.8638 (3)	0.14369 (10)	0.78577 (8)	0.0327 (3)
H3A	1.0078	0.1150	0.8063	0.039*
C4	0.8176 (3)	0.21931 (10)	0.80793 (7)	0.0289 (3)
C5	0.5425 (3)	0.34519 (9)	0.79035 (8)	0.0309 (3)
H5A	0.6481	0.3735	0.8240	0.037*
C6	0.3343 (3)	0.38464 (10)	0.75779 (8)	0.0317 (3)
H6A	0.2971	0.4395	0.7686	0.038*
C7	0.1793 (3)	0.34264 (9)	0.70865 (7)	0.0272 (3)
C8	0.2314 (3)	0.26251 (9)	0.69265 (7)	0.0249 (3)
C9	0.4453 (3)	0.22431 (9)	0.72504 (7)	0.0253 (3)
C10	0.6024 (3)	0.26439 (9)	0.77514 (7)	0.0263 (3)
C11	0.9821 (4)	0.25697 (12)	0.86536 (9)	0.0394 (4)
H11D	1.1244	0.2203	0.8794	0.056 (6)*
H11E	0.8808	0.2659	0.9030	0.066 (7)*
H11F	1.0484	0.3094	0.8512	0.068 (7)*
C12	−0.0603 (3)	0.45274 (10)	0.65301 (8)	0.0300 (3)
C13	−0.3222 (3)	0.46849 (11)	0.61876 (10)	0.0394 (4)
H13A	−0.3207	0.5209	0.5942	0.047*
H13B	−0.4420	0.4744	0.6533	0.047*
C14	−0.4205 (4)	0.40154 (13)	0.56970 (11)	0.0449 (5)
H14A	−0.591 (5)	0.4172 (15)	0.5499 (13)	0.067 (7)*
H14B	−0.433 (4)	0.3504 (13)	0.5928 (11)	0.042 (5)*
C15A	−0.280 (2)	0.3949 (8)	0.5166 (7)	0.0399 (16)	0.55 (2)
C16A	−0.147 (3)	0.3912 (8)	0.4725 (6)	0.059 (2)	0.55 (2)
H16A	−0.0410	0.3882	0.4371	0.071*	0.55 (2)
C15B	−0.228 (3)	0.3822 (10)	0.5170 (8)	0.0399 (16)	0.45 (2)
C16B	−0.084 (3)	0.3704 (10)	0.4775 (8)	0.059 (2)	0.45 (2)
H16B	0.0337	0.3609	0.4455	0.071*	0.45 (2)
C17	0.1254 (3)	0.19905 (9)	0.58756 (7)	0.0258 (3)
C18	−0.0746 (3)	0.14582 (10)	0.55133 (8)	0.0300 (3)
H18A	−0.2420	0.1734	0.5498	0.036*
H18B	−0.0856	0.0939	0.5762	0.036*
C19	−0.0149 (3)	0.12754 (10)	0.48024 (8)	0.0341 (4)
H19A	−0.0120	0.1794	0.4549	0.041*
H19B	0.1567	0.1028	0.4819	0.041*
C20	−0.2013 (4)	0.07199 (10)	0.44457 (8)	0.0360 (4)
C21	−0.3513 (4)	0.02838 (12)	0.41527 (10)	0.0468 (5)
H21	−0.4724	−0.0068	0.3916	0.077 (8)*

	U11	U22	U33	U12	U13	U23
O1	0.0352 (6)	0.0212 (5)	0.0355 (6)	−0.0018 (4)	−0.0082 (5)	−0.0036 (4)
O2	0.0545 (8)	0.0302 (6)	0.0553 (8)	0.0084 (6)	−0.0157 (6)	−0.0085 (6)
O3	0.0307 (6)	0.0262 (6)	0.0396 (6)	−0.0003 (4)	−0.0019 (5)	−0.0005 (5)
O4	0.0330 (6)	0.0369 (7)	0.0538 (8)	−0.0062 (5)	−0.0014 (5)	0.0089 (6)
O5	0.0264 (5)	0.0289 (5)	0.0273 (5)	−0.0056 (4)	−0.0008 (4)	−0.0043 (4)
O6	0.0324 (6)	0.0449 (7)	0.0383 (6)	−0.0130 (5)	0.0061 (5)	−0.0084 (5)
C2	0.0373 (9)	0.0238 (7)	0.0358 (8)	−0.0007 (6)	−0.0042 (7)	0.0024 (6)
C3	0.0333 (8)	0.0288 (8)	0.0341 (8)	−0.0035 (6)	−0.0057 (6)	0.0062 (6)
C4	0.0309 (8)	0.0293 (7)	0.0253 (7)	−0.0089 (6)	−0.0025 (6)	0.0049 (6)
C5	0.0413 (9)	0.0268 (7)	0.0233 (7)	−0.0087 (6)	−0.0024 (6)	−0.0037 (6)
C6	0.0427 (9)	0.0246 (7)	0.0272 (7)	−0.0031 (6)	0.0009 (6)	−0.0033 (6)
C7	0.0307 (7)	0.0258 (7)	0.0250 (7)	−0.0014 (6)	0.0024 (6)	0.0006 (5)
C8	0.0276 (7)	0.0239 (7)	0.0227 (6)	−0.0071 (6)	0.0001 (5)	−0.0018 (5)
C9	0.0312 (7)	0.0192 (6)	0.0249 (7)	−0.0052 (6)	0.0001 (5)	0.0002 (5)
C10	0.0315 (7)	0.0239 (7)	0.0224 (7)	−0.0072 (6)	−0.0018 (5)	0.0015 (5)
C11	0.0410 (9)	0.0414 (10)	0.0324 (8)	−0.0080 (8)	−0.0120 (7)	0.0010 (7)
C12	0.0300 (8)	0.0283 (8)	0.0323 (8)	0.0030 (6)	0.0063 (6)	−0.0008 (6)
C13	0.0309 (8)	0.0318 (9)	0.0544 (11)	0.0021 (7)	−0.0004 (7)	−0.0005 (7)
C14	0.0344 (9)	0.0408 (10)	0.0570 (12)	−0.0078 (8)	−0.0078 (8)	−0.0006 (9)
C15A	0.043 (4)	0.034 (4)	0.0394 (10)	−0.006 (3)	−0.008 (2)	−0.0004 (19)
C16A	0.071 (5)	0.057 (5)	0.051 (2)	−0.017 (3)	0.008 (3)	−0.008 (3)
C15B	0.043 (4)	0.034 (4)	0.0394 (10)	−0.006 (3)	−0.008 (2)	−0.0004 (19)
C16B	0.071 (5)	0.057 (5)	0.051 (2)	−0.017 (3)	0.008 (3)	−0.008 (3)
C17	0.0260 (7)	0.0229 (7)	0.0274 (7)	0.0005 (5)	−0.0014 (5)	−0.0015 (5)
C18	0.0280 (7)	0.0308 (8)	0.0305 (8)	−0.0053 (6)	−0.0002 (6)	−0.0060 (6)
C19	0.0399 (9)	0.0331 (8)	0.0282 (8)	−0.0055 (7)	−0.0009 (6)	−0.0013 (6)
C20	0.0480 (10)	0.0307 (8)	0.0275 (8)	0.0009 (7)	−0.0041 (7)	0.0001 (6)
C21	0.0602 (12)	0.0379 (10)	0.0390 (10)	−0.0072 (9)	−0.0103 (9)	−0.0037 (8)

O1—C9	1.3675 (18)	C11—H11E	0.9800
O1—C2	1.3851 (19)	C11—H11F	0.9800
O2—C2	1.204 (2)	C12—C13	1.501 (2)
O3—C12	1.3682 (19)	C13—C14	1.527 (3)
O3—C7	1.3911 (19)	C13—H13A	0.9900
O4—C12	1.189 (2)	C13—H13B	0.9900
O5—C17	1.3705 (18)	C14—C15A	1.364 (13)
O5—C8	1.3889 (17)	C14—C15B	1.574 (15)
O6—C17	1.1931 (19)	C14—H14A	0.98 (3)
C2—C3	1.446 (2)	C14—H14B	0.96 (2)
C3—C4	1.347 (2)	C15A—C16A	1.186 (9)
C3—H3A	0.9500	C16A—H16A	0.9500
C4—C10	1.453 (2)	C15B—C16B	1.169 (11)
C4—C11	1.501 (2)	C16B—H16B	0.9500
C5—C6	1.379 (2)	C17—C18	1.497 (2)
C5—C10	1.402 (2)	C18—C19	1.521 (2)
C5—H5A	0.9500	C18—H18A	0.9900
C6—C7	1.394 (2)	C18—H18B	0.9900
C6—H6A	0.9500	C19—C20	1.470 (2)
C7—C8	1.385 (2)	C19—H19A	0.9900
C8—C9	1.391 (2)	C19—H19B	0.9900
C9—C10	1.3977 (19)	C20—C21	1.177 (3)
C11—H11D	0.9800	C21—H21	0.9500
C9—O1—C2	120.77 (12)	O3—C12—C13	109.55 (14)
C12—O3—C7	121.60 (12)	C12—C13—C14	113.95 (15)
C17—O5—C8	117.86 (11)	C12—C13—H13A	108.8
O2—C2—O1	116.59 (14)	C14—C13—H13A	108.8
O2—C2—C3	126.42 (16)	C12—C13—H13B	108.8
O1—C2—C3	116.97 (14)	C14—C13—H13B	108.8
C4—C3—C2	123.07 (15)	H13A—C13—H13B	107.7
C4—C3—H3A	118.5	C15A—C14—C13	112.6 (6)
C2—C3—H3A	118.5	C13—C14—C15B	112.2 (7)
C3—C4—C10	118.56 (14)	C15A—C14—H14A	104.9 (16)
C3—C4—C11	121.39 (15)	C13—C14—H14A	107.9 (15)
C10—C4—C11	120.05 (14)	C15B—C14—H14A	114.3 (16)
C6—C5—C10	121.75 (14)	C15A—C14—H14B	112.2 (14)
C6—C5—H5A	119.1	C13—C14—H14B	110.5 (13)
C10—C5—H5A	119.1	C15B—C14—H14B	103.3 (14)
C5—C6—C7	118.88 (14)	H14A—C14—H14B	108.4 (19)
C5—C6—H6A	120.6	C16A—C15A—C14	176.4 (14)
C7—C6—H6A	120.6	C15A—C16A—H16A	180.0
C8—C7—O3	114.71 (13)	C16B—C15B—C14	177.9 (16)
C8—C7—C6	121.01 (14)	C15B—C16B—H16B	180.0
O3—C7—C6	124.13 (14)	O6—C17—O5	123.07 (13)
C7—C8—O5	119.98 (13)	O6—C17—C18	127.00 (14)
C7—C8—C9	119.26 (13)	O5—C17—C18	109.93 (13)
O5—C8—C9	120.45 (13)	C17—C18—C19	111.39 (13)
O1—C9—C8	116.28 (12)	C17—C18—H18A	109.4
O1—C9—C10	122.63 (14)	C19—C18—H18A	109.4
C8—C9—C10	121.07 (13)	C17—C18—H18B	109.4
C9—C10—C5	117.99 (14)	C19—C18—H18B	109.4
C9—C10—C4	117.62 (14)	H18A—C18—H18B	108.0
C5—C10—C4	124.39 (13)	C20—C19—C18	112.58 (14)
C4—C11—H11D	109.5	C20—C19—H19A	109.1
C4—C11—H11E	109.5	C18—C19—H19A	109.1
H11D—C11—H11E	109.5	C20—C19—H19B	109.1
C4—C11—H11F	109.5	C18—C19—H19B	109.1
H11D—C11—H11F	109.5	H19A—C19—H19B	107.8
H11E—C11—H11F	109.5	C21—C20—C19	179.00 (19)
O4—C12—O3	124.34 (15)	C20—C21—H21	180.0
O4—C12—C13	126.10 (15)
C9—O1—C2—O2	−174.76 (15)	O5—C8—C9—C10	−171.09 (13)
C9—O1—C2—C3	6.7 (2)	O1—C9—C10—C5	179.15 (14)
O2—C2—C3—C4	178.29 (18)	C8—C9—C10—C5	−2.0 (2)
O1—C2—C3—C4	−3.3 (2)	O1—C9—C10—C4	−0.8 (2)
C2—C3—C4—C10	−2.0 (2)	C8—C9—C10—C4	178.12 (13)
C2—C3—C4—C11	177.73 (16)	C6—C5—C10—C9	0.6 (2)
C10—C5—C6—C7	0.3 (2)	C6—C5—C10—C4	−179.52 (15)
C12—O3—C7—C8	−141.36 (14)	C3—C4—C10—C9	4.1 (2)
C12—O3—C7—C6	43.1 (2)	C11—C4—C10—C9	−175.69 (14)
C5—C6—C7—C8	0.3 (2)	C3—C4—C10—C5	−175.83 (15)
C5—C6—C7—O3	175.49 (14)	C11—C4—C10—C5	4.4 (2)
O3—C7—C8—O5	−3.7 (2)	C7—O3—C12—O4	−1.9 (2)
C6—C7—C8—O5	171.99 (14)	C7—O3—C12—C13	179.10 (14)
O3—C7—C8—C9	−177.27 (13)	O4—C12—C13—C14	134.73 (19)
C6—C7—C8—C9	−1.6 (2)	O3—C12—C13—C14	−46.3 (2)
C17—O5—C8—C7	111.09 (16)	C12—C13—C14—C15A	−64.6 (6)
C17—O5—C8—C9	−75.36 (17)	C12—C13—C14—C15B	−53.0 (7)
C2—O1—C9—C8	176.26 (14)	C8—O5—C17—O6	−4.2 (2)
C2—O1—C9—C10	−4.8 (2)	C8—O5—C17—C18	174.99 (12)
C7—C8—C9—O1	−178.55 (13)	O6—C17—C18—C19	−4.7 (2)
O5—C8—C9—O1	7.9 (2)	O5—C17—C18—C19	176.16 (13)
C7—C8—C9—C10	2.5 (2)	C17—C18—C19—C20	177.12 (14)

D—H···A	D—H	H···A	D···A	D—H···A
C13—H13B···O4i	0.99	2.43	3.244 (2)	139
C18—H18A···O6i	0.99	2.51	3.482 (2)	167