(1R,3S)-1-Mono­amido­camphoric acid

The title compound, (1S,3R)-3-carbamoyl-2,2,3-tri­methyl­cyclo­pentane-1-carboxyl­ic acid, C₁₀H₁₇NO₃, was synthesized and characterized by IR, EA, ES–MS (electrospray ionization mass spectra), ¹H NMR, ¹³C NMR and X-ray diffraction techniques. The two independent mol­ecules form a two-dimensional network via O—H...O and N—H...O hydrogen-bonding interactions between their carbox­ylic acid and carbamoyl groups.

S1. Comment

Camphoric acids and their derivatives, especially those having specific absolute configurations, are very useful intermediates in organic synthesis (Nieto et al., 1998), and can be used as building blocks in self-assembly studies via coordinative and hydrogen bonds, thus generating interesting topologies and functions. For example, D-(+)-camphoric acid has been used in self-assembly with certain organic acids (Hu et al., 2001) or polyamines (Goswami et al., 2000; Zakaria et al., 2003) by means of hydrogen-bonding interactions.

While racemic 3-monoamidocamphoric acid can be obtained from camphoric anhydride, racemic 1-monoamidocamphoric acid can be prepared from camphoric imide (Noyes, 1894) by a method which has been improved, simplified and further characterized in our experiments. The crystallographic data of the title compound, (I) [also known as (1R,3S)-β-camphoramic acid] is different to that of (1R,3S)-3-monoamidocamphoric acid [or (1R,3S)-α-camphoramic acid], synthesized via an alternative method from (1R,3S)-camphoric acid (Nie et al., 2002). The results of the IR, microanalytical, ES–MS, ¹H NMR and ¹³C NMR analyses of (1R,3S)-β-camphoramic acid and its optical rotation value confirm the formulation and absolute configuration.

The atom-numbering scheme for (I) is shown in Fig. 1, while selected bond distances and angles are given in Table 1. There are two crystallographically independent molecules per asymmetric unit in the orthorhombic chiral space group P2₁2₁2₁. The absolute configuration shown is that determined by its optical rotation value [α]_D²⁰ = + 73.3° (C = 1, C₂H₅OH), which is consistent with the value in the literature (CRC Handbook of Chemistry and Physics, 1988–1989). The ring geometies are similar to those of (1R,3S)-3-monoamidocamphoric acid reported by Nie et al. (2002), with elongations of the C—C bonds and C—C—C bond-angle contractions of the `flap' quaternary atoms in the five-membered rings (C2 and C12). Bond lengths related to the carboxylic acid groups also exhibit electron-delocalization because of their conjugate interactions. Changing the positions of the carboxylic acid group and the acylamino group leads to higher values of R1 and wR2 (0.065 and 0.146, respectively) and of the displacement parameters, thus confirming the (1R,3S)-1-monoamidocamphoric acid formulation.

The crystal packing involves three kinds of traditional hydrogen-bonding interactions, as well as weak C—H···O interactions(Table 2). Hydrogen-bonding interactions between the carboxyl and acylamide groups (O2—H1···O3, O5—H2···O6 and N1—H1A···O1, N2—H2A···O4) form eight-membered rings along the c axis. Hydrogen bonds associated with the N and O atoms of adjacent acylamides (N1—H1B···O6 and N2—H2B···O3) along the a axis are also observed. The resulting two-dimensional layers formed are not planar, but form a ripple along the c direction. This is different from the crystal packing of (1R,3S)-3-monoamid-camphoric acid in which a three-dimensional hydrogen-bond-supported framework is found.

S2. Experimental

(1R,3S)-1-Monoamide-camphoric acid was synthesized successfully from D-(+)-camphoric imide via a simplified version of the method reported by Noyes (1894). Treatment of D-(+)-camphoric imide (1.81 g, 10 mmol) with sodium hydroxide (2.0 g, 50 mmol) in water under reflux for 2 h gave a solution of the sodium salt of (1R,3S)-1-monoamide-camphoric acid. After being cooled to room temperature, the mixture was carefully acidified with hydrochloric acid (2 mol l⁻¹), and the resulting white precipitates [(1R,3S)-1-monoamide-camphoric acid] were collected and recrystallized in ethanol/water (yield 1.22 g, 61.3%; m.p. 452–454 K. Analysis calculated for C₁₀H₁₇NO₃: C 60.28, H 8.60, N 7.03; found: C 59.91, H 8.60, N 6.93. Main FT–IR (KBr plates, cm⁻¹): 3475, 3415, 3224, 3235, 3195, 2982, 2971, 1709, 1693, 1644 and 1389 (all strong peaks); ¹H NMR (d⁶-DMSO): δ 0.74 (s, 3H, Me), 1.08 (s, 3H, Me), 1.18 (s, 3H, Me), 1.43 (m, 1H, CH₂), 1.65 (m, 1H, CH₂), 1.98 (t, 1H, CH₂), 2.39 (t, 1H, CH₂), 2.63 (t, 1H, CH), 3.29 (s, 2H, CONH₂), 6.65 (s, 1H, COOH); ¹³C NMR (d⁶-DMSO): δ 26.36, 26.94, 27.68, 28.48, 37.86, 51.39, 57.70, 60.77, 180.83, 182.85; Es-ms: m/z [C₁₀H₁₇NO₃H]⁺ 200 (100%). [α]_D²⁰ = + 73.3° (C = 1 g/100 mL, C₂H₅OH). Elemental analysis was performed with a Perkin-Elmer 1400 C analyzer, IR spectra (4000–400 cm⁻¹) were recorded on a Nicolet FT–IR 170X spectrophotometer, NMR spectra were obtained with a Bruker 500 MHz NMR spectrometer, electrospray ionization mass spectra were obtained with a Finnigan MAT SSQ 710 mass spectrometer in a scan range 300–1200 a.m.u. and the optical rotation values were determined via a WZZ-115 digital auto-polarimeter.

S3. Refinement

The positions of all H atoms were fixed geometrically with C—H distances of 0.96 Å, N—H distances of 0.86 Å and O—H distances of 0.85 Å.

Computing details

Data collection: SMART (Bruker 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A view of (I), showing the atom-numbering scheme and displacement ellipsoids at the 30% probability level.
	Fig. 2. A perspective view of the crystal packing of (I), approximately along the b axis. For clarity, labels are given only once for the hydrogen-bond contacts (see Table 2).

(1S,3R)-3-Carbamoyl-2,2,3-trimethylcyclopentane-1-carboxylic acid

Crystal data

C10H17NO3	F(000) = 864
Mr = 199.25	Dx = 1.242 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 871 reflections
a = 10.400 (2) Å	θ = 2.8–20.1°
b = 12.810 (3) Å	µ = 0.09 mm^−1
c = 16.000 (3) Å	T = 293 K
V = 2131.6 (8) Å^3	Slab, colorless
Z = 8	0.40 × 0.30 × 0.20 mm

Data collection

Bruker CCD area-detector diffractometer	2873 independent reflections
Radiation source: fine-focus sealed tube	1653 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.078
ϕ and ω scans	θmax = 28.1°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −13→13
Tmin = 0.968, Tmax = 0.982	k = −16→16
12841 measured reflections	l = −14→20

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 0.87	w = 1/[σ^2(Fo^2) + (0.0396P)^2] where P = (Fo^2 + 2Fc^2)/3
2873 reflections	(Δ/σ)max < 0.001
253 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.19 e Å^−3

Special details

Experimental. The structure was solved by direct methods (Bruker, 2000) and successive difference Fourier syntheses.

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
C1	0.7058 (2)	0.3940 (2)	0.84114 (15)	0.0354 (6)
C2	0.7895 (2)	0.4071 (2)	0.92181 (15)	0.0335 (6)
C3	0.7271 (2)	0.3249 (2)	0.98221 (15)	0.0374 (7)
H3A	0.7711	0.2583	0.9727	0.045*
C4	0.5875 (3)	0.3111 (2)	0.95373 (16)	0.0511 (8)
H4A	0.5710	0.2388	0.9392	0.061*
H4B	0.5287	0.3315	0.9979	0.061*
C5	0.5703 (3)	0.3810 (3)	0.87756 (16)	0.0481 (8)
H5A	0.5348	0.4481	0.8936	0.058*
H5B	0.5134	0.3487	0.8371	0.058*
C6	0.7469 (2)	0.3530 (2)	1.07212 (17)	0.0350 (7)
C7	0.7197 (3)	0.4848 (2)	0.78110 (16)	0.0359 (7)
C8	0.7417 (3)	0.2972 (3)	0.79094 (19)	0.0640 (10)
H8A	0.6879	0.2927	0.7424	0.096*
H8B	0.7299	0.2362	0.8249	0.096*
H8C	0.8301	0.3019	0.7740	0.096*
C9	0.7768 (3)	0.5183 (2)	0.95574 (17)	0.0504 (8)
H9A	0.8158	0.5663	0.9173	0.076*
H9B	0.8191	0.5230	1.0089	0.076*
H9C	0.6874	0.5353	0.9623	0.076*
C10	0.9322 (2)	0.3846 (3)	0.91017 (17)	0.0612 (10)
H10A	0.9688	0.4355	0.8732	0.092*
H10B	0.9429	0.3162	0.8867	0.092*
H10C	0.9748	0.3879	0.9633	0.092*
C11	0.2475 (2)	0.3869 (2)	0.66828 (16)	0.0384 (7)
C12	0.1953 (2)	0.4103 (2)	0.57783 (15)	0.0352 (7)
C13	0.2649 (2)	0.3239 (2)	0.52581 (15)	0.0359 (7)
H13A	0.2126	0.2604	0.5290	0.043*
C14	0.3926 (3)	0.3016 (2)	0.56983 (17)	0.0531 (9)
H14A	0.4019	0.2274	0.5805	0.064*
H14B	0.4642	0.3246	0.5357	0.064*
C15	0.3884 (3)	0.3622 (3)	0.65165 (17)	0.0618 (10)
H15A	0.4380	0.4261	0.6470	0.074*
H15B	0.4238	0.3206	0.6968	0.074*
C16	0.2799 (3)	0.3517 (2)	0.43490 (18)	0.0416 (7)
C17	0.2343 (3)	0.4803 (2)	0.72694 (16)	0.0376 (7)
C18	0.1822 (3)	0.2933 (2)	0.70927 (19)	0.0694 (11)
H18A	0.2178	0.2824	0.7639	0.104*
H18B	0.1961	0.2322	0.6757	0.104*
H18C	0.0916	0.3064	0.7139	0.104*
C19	0.2370 (3)	0.5190 (2)	0.55021 (19)	0.0628 (10)
H19A	0.2044	0.5327	0.4952	0.094*
H19B	0.3291	0.5227	0.5496	0.094*
H19C	0.2036	0.5699	0.5885	0.094*
C20	0.0497 (2)	0.4005 (3)	0.56911 (17)	0.0626 (10)
H20A	0.0251	0.4158	0.5126	0.094*
H20B	0.0085	0.4487	0.6063	0.094*
H20D	0.0239	0.3306	0.5829	0.094*
N1	0.6154 (2)	0.53641 (19)	0.75811 (14)	0.0482 (7)
H1A	0.6212	0.5866	0.7226	0.058*
H1B	0.5418	0.5198	0.7786	0.058*
N2	0.1173 (2)	0.5117 (2)	0.74708 (13)	0.0510 (7)
H2A	0.1071	0.5627	0.7815	0.061*
H2B	0.0513	0.4813	0.7258	0.061*
O1	0.84661 (18)	0.33983 (17)	1.10820 (11)	0.0574 (6)
O2	0.64617 (17)	0.39390 (17)	1.10895 (11)	0.0541 (6)
H1	0.6646	0.4076	1.1595	0.081*
O3	0.82536 (17)	0.50865 (16)	0.75165 (11)	0.0486 (5)
O4	0.38118 (19)	0.36362 (19)	0.39985 (12)	0.0630 (7)
O5	0.16833 (18)	0.36150 (17)	0.39614 (11)	0.0539 (6)
H2	0.1765	0.3977	0.3431	0.081*
O6	0.32943 (17)	0.52418 (16)	0.75759 (12)	0.0497 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0440 (16)	0.0342 (17)	0.0280 (15)	−0.0040 (14)	−0.0026 (12)	0.0026 (13)
C2	0.0344 (14)	0.0385 (17)	0.0277 (14)	−0.0019 (13)	−0.0018 (11)	0.0048 (13)
C3	0.0518 (17)	0.0318 (17)	0.0287 (16)	−0.0001 (14)	−0.0006 (13)	−0.0002 (13)
C4	0.0604 (19)	0.059 (2)	0.0339 (17)	−0.0238 (16)	−0.0050 (15)	0.0088 (15)
C5	0.0455 (17)	0.064 (2)	0.0350 (16)	−0.0162 (15)	−0.0077 (13)	0.0071 (16)
C6	0.0405 (17)	0.0363 (17)	0.0282 (15)	0.0056 (13)	0.0031 (12)	0.0040 (13)
C7	0.0360 (16)	0.0434 (19)	0.0282 (15)	−0.0002 (14)	−0.0047 (13)	0.0017 (13)
C8	0.107 (3)	0.049 (2)	0.0361 (19)	0.001 (2)	−0.0041 (18)	−0.0085 (16)
C9	0.074 (2)	0.0398 (19)	0.0368 (17)	−0.0102 (17)	−0.0079 (15)	0.0034 (15)
C10	0.0464 (18)	0.087 (3)	0.050 (2)	0.0061 (18)	0.0009 (15)	0.025 (2)
C11	0.0441 (16)	0.0428 (19)	0.0282 (15)	0.0043 (14)	−0.0067 (12)	0.0004 (14)
C12	0.0404 (16)	0.0363 (17)	0.0290 (15)	0.0038 (14)	−0.0056 (12)	0.0000 (13)
C13	0.0447 (16)	0.0342 (17)	0.0289 (16)	0.0015 (13)	−0.0022 (13)	0.0002 (13)
C14	0.0571 (19)	0.064 (2)	0.0380 (18)	0.0246 (17)	−0.0072 (15)	−0.0107 (16)
C15	0.0570 (19)	0.090 (3)	0.0385 (18)	0.0332 (19)	−0.0135 (15)	−0.0216 (18)
C16	0.0506 (18)	0.0396 (19)	0.0348 (17)	0.0026 (15)	−0.0048 (15)	−0.0048 (14)
C17	0.0422 (17)	0.047 (2)	0.0235 (15)	0.0072 (15)	0.0010 (13)	−0.0024 (14)
C18	0.121 (3)	0.044 (2)	0.043 (2)	0.004 (2)	0.012 (2)	0.0063 (16)
C19	0.103 (3)	0.040 (2)	0.0451 (19)	−0.0003 (19)	0.0040 (18)	0.0027 (16)
C20	0.0474 (18)	0.091 (3)	0.0496 (19)	0.0116 (19)	−0.0103 (14)	−0.022 (2)
N1	0.0389 (13)	0.0588 (17)	0.0470 (16)	−0.0003 (12)	0.0052 (12)	0.0212 (13)
N2	0.0390 (14)	0.0676 (18)	0.0464 (15)	−0.0016 (13)	−0.0006 (11)	−0.0219 (15)
O1	0.0494 (13)	0.0886 (17)	0.0343 (12)	0.0252 (12)	−0.0067 (10)	−0.0116 (12)
O2	0.0485 (12)	0.0762 (16)	0.0377 (12)	0.0144 (12)	−0.0054 (9)	−0.0156 (12)
O3	0.0358 (11)	0.0708 (15)	0.0393 (12)	0.0001 (10)	0.0023 (9)	0.0204 (11)
O4	0.0512 (13)	0.0928 (18)	0.0449 (13)	0.0071 (12)	0.0094 (10)	0.0161 (12)
O5	0.0492 (12)	0.0808 (16)	0.0319 (11)	−0.0081 (11)	−0.0070 (10)	0.0078 (11)
O6	0.0375 (11)	0.0653 (14)	0.0462 (13)	−0.0050 (10)	−0.0006 (10)	−0.0193 (12)

Geometric parameters (Å, º)

C1—C7	1.516 (4)	C11—C12	1.575 (3)
C1—C8	1.524 (4)	C12—C19	1.523 (4)
C1—C5	1.534 (4)	C12—C20	1.525 (4)
C1—C2	1.566 (3)	C12—C13	1.563 (4)
C2—C10	1.523 (4)	C13—C16	1.506 (4)
C2—C9	1.530 (4)	C13—C14	1.530 (3)
C2—C3	1.569 (4)	C13—H13A	0.9800
C3—C6	1.497 (4)	C14—C15	1.522 (4)
C3—C4	1.532 (4)	C14—H14A	0.9700
C3—H3A	0.9800	C14—H14B	0.9700
C4—C5	1.523 (4)	C15—H15A	0.9700
C4—H4A	0.9700	C15—H15B	0.9700
C4—H4B	0.9700	C16—O4	1.203 (3)
C5—H5A	0.9700	C16—O5	1.322 (3)
C5—H5B	0.9700	C17—O6	1.239 (3)
C6—O1	1.199 (3)	C17—N2	1.322 (3)
C6—O2	1.311 (3)	C18—H18A	0.9600
C7—O3	1.234 (3)	C18—H18B	0.9600
C7—N1	1.323 (3)	C18—H18C	0.9600
C8—H8A	0.9600	C19—H19A	0.9600
C8—H8B	0.9600	C19—H19B	0.9600
C8—H8C	0.9600	C19—H19C	0.9600
C9—H9A	0.9600	C20—H20A	0.9600
C9—H9B	0.9600	C20—H20B	0.9600
C9—H9C	0.9600	C20—H20D	0.9600
C10—H10A	0.9600	N1—H1A	0.8600
C10—H10B	0.9600	N1—H1B	0.8600
C10—H10C	0.9600	N2—H2A	0.8600
C11—C15	1.523 (4)	N2—H2B	0.8600
C11—C18	1.526 (4)	O2—H1	0.8500
C11—C17	1.527 (4)	O5—H2	0.9711
C7—C1—C8	105.5 (2)	C18—C11—C12	113.0 (2)
C7—C1—C5	114.3 (2)	C17—C11—C12	112.6 (2)
C8—C1—C5	109.7 (2)	C19—C12—C20	109.4 (2)
C7—C1—C2	112.8 (2)	C19—C12—C13	111.2 (2)
C8—C1—C2	112.7 (2)	C20—C12—C13	110.6 (2)
C5—C1—C2	102.1 (2)	C19—C12—C11	110.0 (2)
C10—C2—C9	107.7 (2)	C20—C12—C11	114.3 (2)
C10—C2—C1	114.9 (2)	C13—C12—C11	101.2 (2)
C9—C2—C1	110.1 (2)	C16—C13—C14	113.5 (2)
C10—C2—C3	110.5 (2)	C16—C13—C12	113.3 (2)
C9—C2—C3	111.7 (2)	C14—C13—C12	106.8 (2)
C1—C2—C3	101.9 (2)	C16—C13—H13A	107.7
C6—C3—C4	116.4 (2)	C14—C13—H13A	107.7
C6—C3—C2	111.9 (2)	C12—C13—H13A	107.7
C4—C3—C2	106.6 (2)	C15—C14—C13	106.0 (2)
C6—C3—H3A	107.2	C15—C14—H14A	110.5
C4—C3—H3A	107.2	C13—C14—H14A	110.5
C2—C3—H3A	107.2	C15—C14—H14B	110.5
C5—C4—C3	106.3 (2)	C13—C14—H14B	110.5
C5—C4—H4A	110.5	H14A—C14—H14B	108.7
C3—C4—H4A	110.5	C14—C15—C11	106.5 (2)
C5—C4—H4B	110.5	C14—C15—H15A	110.4
C3—C4—H4B	110.5	C11—C15—H15A	110.4
H4A—C4—H4B	108.7	C14—C15—H15B	110.4
C4—C5—C1	105.1 (2)	C11—C15—H15B	110.4
C4—C5—H5A	110.7	H15A—C15—H15B	108.6
C1—C5—H5A	110.7	O4—C16—O5	122.5 (3)
C4—C5—H5B	110.7	O4—C16—C13	124.8 (3)
C1—C5—H5B	110.7	O5—C16—C13	112.6 (3)
H5A—C5—H5B	108.8	O6—C17—N2	120.0 (3)
O1—C6—O2	122.1 (3)	O6—C17—C11	121.8 (2)
O1—C6—C3	123.2 (2)	N2—C17—C11	118.1 (3)
O2—C6—C3	114.7 (2)	C11—C18—H18A	109.5
O3—C7—N1	120.0 (2)	C11—C18—H18B	109.5
O3—C7—C1	121.1 (2)	H18A—C18—H18B	109.5
N1—C7—C1	118.8 (2)	C11—C18—H18C	109.5
C1—C8—H8A	109.5	H18A—C18—H18C	109.5
C1—C8—H8B	109.5	H18B—C18—H18C	109.5
H8A—C8—H8B	109.5	C12—C19—H19A	109.5
C1—C8—H8C	109.5	C12—C19—H19B	109.5
H8A—C8—H8C	109.5	H19A—C19—H19B	109.5
H8B—C8—H8C	109.5	C12—C19—H19C	109.5
C2—C9—H9A	109.5	H19A—C19—H19C	109.5
C2—C9—H9B	109.5	H19B—C19—H19C	109.5
H9A—C9—H9B	109.5	C12—C20—H20A	109.5
C2—C9—H9C	109.5	C12—C20—H20B	109.5
H9A—C9—H9C	109.5	H20A—C20—H20B	109.5
H9B—C9—H9C	109.5	C12—C20—H20D	109.5
C2—C10—H10A	109.5	H20A—C20—H20D	109.5
C2—C10—H10B	109.5	H20B—C20—H20D	109.5
H10A—C10—H10B	109.5	C7—N1—H1A	120.0
C2—C10—H10C	109.5	C7—N1—H1B	120.0
H10A—C10—H10C	109.5	H1A—N1—H1B	120.0
H10B—C10—H10C	109.5	C17—N2—H2A	120.0
C15—C11—C18	109.9 (3)	C17—N2—H2B	120.0
C15—C11—C17	110.9 (2)	H2A—N2—H2B	120.0
C18—C11—C17	108.1 (2)	C6—O2—H1	109.2
C15—C11—C12	102.2 (2)	C16—O5—H2	112.3

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1···O3^i	0.85	1.83	2.619 (3)	155
N1—H1A···O1^ii	0.86	2.09	2.902 (3)	158
N1—H1B···O6	0.86	2.23	2.978 (3)	145
O5—H2···O6^iii	0.97	1.70	2.657 (3)	170
N2—H2A···O4^iv	0.86	2.12	2.920 (3)	155
N2—H2B···O3^v	0.86	2.41	3.037 (3)	130
C4—H4B···O2	0.97	2.30	2.769 (3)	109
C14—H14B···O4	0.97	2.39	2.836 (4)	107
C20—H20A···O5	0.96	2.48	3.071 (3)	119
C20—H20B···O2^iii	0.96	2.58	3.391 (4)	142

Symmetry codes: (i) −x+3/2, −y+1, z+1/2; (ii) −x+3/2, −y+1, z−1/2; (iii) −x+1/2, −y+1, z−1/2; (iv) −x+1/2, −y+1, z+1/2; (v) x−1, y, z.