tert-Butyl 4-isopropyl-2-oxo-6-phenyl-3,4-dihydro-2H-pyran-3-carboxyl­ate

Chen, W.; Yu, M.; Li, S.; Jiao, N.

doi:10.1107/S160053681001367X

organic compounds

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ISSN: 2056-9890

Volume 66| Part 5| May 2010| Page o1103

https://doi.org/10.1107/S160053681001367X

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tert-Butyl 4-isopropyl-2-oxo-6-phenyl-3,4-dihydro-2H-pyran-3-carboxylate

Wei Chen,^a Miao Yu,^b ^* Si Li ^c and Ning Jiao ^c

^aChinese PLA Postgraduate Medical School, No. 28 Fuxing Road, Beijing 100853, People's Republic of China, ^bDepartment of Radiology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, People's Republic of China, and ^cState Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Xue Yuan Rd 38, Beijing 100191, People's Republic of China
^*Correspondence e-mail: yumiao301@gmail.com

(Received 23 February 2010; accepted 13 April 2010; online 17 April 2010)

In the title compound, C₁₉H₂₄O₄, the six-membered lactone ring adopts an envelope conformation with the tert-butoxycarbonyl and isopropyl substituents in axial positions, and the phenyl group in an equatorial position. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers.

Related literature

For the applications and synthesis of endocyclic enol lactones, see: Davies & Jin (2004 ); Evans et al. (2005 ); Krafft & Katzenellenbogen (1981 ); Li et al. (2007 ); Zeni et al. (2004 ); Zhao et al. (1997 ); Jimenez-Tenorio et al. (2001 ). For the synthesis, see: Li et al. (2009 ).

Experimental

Crystal data

C₁₉H₂₄O₄
M_r = 316.38
Triclinic, $[P \overline 1]$
a = 8.6163 (9) Å
b = 10.888 (1) Å
c = 11.261 (1) Å
α = 68.393 (2)°
β = 79.118 (2)°
γ = 67.998 (2)°
V = 909.09 (15) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.48 × 0.46 × 0.42 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ) T_min = 0.760, T_max = 1.000
4986 measured reflections
3510 independent reflections
2759 reflections with I > 2σ(I)
R_int = 0.051

Refinement

R[F² > 2σ(F²)] = 0.055
wR(F²) = 0.158
S = 1.04
3510 reflections
213 parameters
H-atom parameters constrained
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯O1ⁱ	0.98	2.44	3.407 (2)	170
Symmetry code: (i) -x, -y+2, -z+1.

Data collection: SMART (Bruker, 2001 ); cell refinement: SAINT (Bruker, 2001); data reduction: SHELXTL (Sheldrick, 2008 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and DIAMOND (Brandenburg, 1998 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S160053681001367X/lx2139sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681001367X/lx2139Isup2.hkl

checkCIF report

Comment top

Endocyclic enol lactones are important structural elements of biologically active natural products (Zhao et al., 1997) and useful synthetic intermediates for organic synthesis (Evans et al., 2005, Davies et al., 2004). The cyclization of alkynoic acids under acidic conditions (Krafft et al., 1981) , employing transition-metal complexes as catalysts (Zeni et al., 2004, Valerga et al., 2001),and the carbonylation coupling of alkynes and 1,3-dicarbonyl compounds are main synthetic pathways for the preparation of Enol lactones (Li et al., 2007)

In the title compound as shown in Fig. 1, the six-membered lactone ring adopts an envelope conformation with the tert-butoxycarbonyl, isopropyl and phenyl groups attached to it. The tert-butoxycarbonyl and isopropyl groups occupy axial positions, and the phenyl group occupies equatorial position. The crystal packing (Fig. 2) is stabilized by weak intermolecular C—H···O hydrogen bonds between the pyran H atom and the oxygen of the C═O unit in pyran ring, with a C2—H2···O1ⁱ (Table 1).

Related literature top

For the applications and synthesis of endocyclic enol lactones, see: Davies et al. (2004); Evans et al. (2005); Krafft et al. (1981); Li et al. (2007); Zeni et al. (2004); Zhao et al. (1997); Jimenez-Tenorio et al. (2001). For the synthesis, see: Li et al. (2009).

Experimental top

The title compound was obtained as a by-product in the copper-catalyzed tandem conjugate addition–cyclization–hydrolysis–decarboxylation reactions of alkynes and 5-alkylidene-Meldrum's acids (Jiao et al., 2009) acids as follows: To a mixture of CuBr (20 mg, 0.1 mmol), 1-ethynylbenzene (102 mg, 1 mmol) in H₂O : t-BuOH = 10 : 1 (3 ml) was added and 2,2-dimethyl-5-(2-methylpropylidene)-1,3-dioxane-4,6-dione (99 mg, 0.5 mmol) at room temperature. The resulting mixture was refluxed for 10 h monitored by TLC. After evaporation, the residue was carefully purified by flash chromatography on silica gel. The title compound was obtained as a by-product (25% yield), which was crystallized from n-hexane-ethyl acetate.

Structure description top

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SHELXTL (Sheldrick, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as a small spheres of arbitrary radius.
	Fig. 2. C—H···O interactions (dotted lines) in the crystal structure of the title compound. [Symmetry codes: (i) - x, - y + 2, - z + 1.]

tert-Butyl 4-isopropyl-2-oxo-6-phenyl-3,4-dihydro-2H-pyran-3-carboxylate top

Crystal data top

C₁₉H₂₄O₄	Z = 2
M_r = 316.38	F(000) = 340
Triclinic, P1	D_x = 1.156 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.6163 (9) Å	Cell parameters from 2216 reflections
b = 10.888 (1) Å	θ = 4.8–55.3°
c = 11.261 (1) Å	µ = 0.08 mm⁻¹
α = 68.393 (2)°	T = 293 K
β = 79.118 (2)°	Prismatic, colorless
γ = 67.998 (2)°	0.48 × 0.46 × 0.42 mm
V = 909.09 (15) Å³

Data collection top

Bruker SMART CCD area-detector diffractometer	3510 independent reflections
Radiation source: fine-focus sealed tube	2759 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.051
Detector resolution: 10.0 pixels mm^-1	θ_max = 26.0°, θ_min = 2.0°
φ and ω scans	h = −10→10
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	k = −10→13
T_min = 0.760, T_max = 1.000	l = −13→12
4986 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.158	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0925P)² + 0.0377P] where P = (F_o² + 2F_c²)/3
3510 reflections	(Δ/σ)_max < 0.001
213 parameters	Δρ_max = 0.22 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₉H₂₄O₄	γ = 67.998 (2)°
M_r = 316.38	V = 909.09 (15) Å³
Triclinic, P1	Z = 2
a = 8.6163 (9) Å	Mo Kα radiation
b = 10.888 (1) Å	µ = 0.08 mm⁻¹
c = 11.261 (1) Å	T = 293 K
α = 68.393 (2)°	0.48 × 0.46 × 0.42 mm
β = 79.118 (2)°

Data collection top

Bruker SMART CCD area-detector diffractometer	3510 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	2759 reflections with I > 2σ(I)
T_min = 0.760, T_max = 1.000	R_int = 0.051
4986 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.055	0 restraints
wR(F²) = 0.158	H-atom parameters constrained
S = 1.04	Δρ_max = 0.22 e Å⁻³
3510 reflections	Δρ_min = −0.21 e Å⁻³
213 parameters

Special details top

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.

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 > 2sigma(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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	−0.04144 (14)	0.87317 (11)	0.66284 (11)	0.0535 (3)
O2	0.07228 (13)	0.64576 (11)	0.71597 (10)	0.0461 (3)
O3	0.48770 (16)	0.75686 (16)	0.51105 (14)	0.0721 (4)
O4	0.33639 (14)	0.77581 (13)	0.69310 (12)	0.0554 (3)
C1	0.06511 (19)	0.77682 (15)	0.63769 (14)	0.0408 (4)
C2	0.19583 (19)	0.78720 (16)	0.52821 (14)	0.0425 (4)
H2	0.1560	0.8805	0.4644	0.051*
C3	0.2282 (2)	0.67697 (16)	0.46303 (15)	0.0441 (4)
H3	0.3364	0.6694	0.4143	0.053*
C4	0.2483 (2)	0.53947 (16)	0.56580 (15)	0.0450 (4)
H4	0.3113	0.4581	0.5464	0.054*
C5	0.18081 (19)	0.52752 (15)	0.68321 (15)	0.0412 (4)
C6	0.3589 (2)	0.77079 (16)	0.57572 (16)	0.0470 (4)
C7	0.4744 (3)	0.7625 (3)	0.7630 (2)	0.0739 (6)
C8	0.5394 (3)	0.8833 (3)	0.6928 (3)	0.0982 (9)
H8A	0.5896	0.8764	0.6108	0.147*
H8B	0.6216	0.8799	0.7418	0.147*
H8C	0.4481	0.9703	0.6812	0.147*
C9	0.3851 (4)	0.7727 (4)	0.8901 (2)	0.1092 (10)
H9A	0.2958	0.8610	0.8764	0.164*
H9B	0.4630	0.7658	0.9448	0.164*
H9C	0.3398	0.6978	0.9296	0.164*
C10	0.6078 (4)	0.6211 (3)	0.7773 (4)	0.1282 (12)
H10A	0.5556	0.5509	0.8000	0.192*
H10B	0.6796	0.5992	0.8432	0.192*
H10C	0.6730	0.6233	0.6979	0.192*
C11	0.0973 (2)	0.7132 (2)	0.36787 (17)	0.0589 (5)
H11	0.1194	0.6283	0.3467	0.071*
C12	0.1187 (4)	0.8256 (3)	0.2436 (2)	0.0887 (8)
H12A	0.0410	0.8410	0.1845	0.133*
H12B	0.2312	0.7957	0.2076	0.133*
H12C	0.0976	0.9111	0.2601	0.133*
C13	−0.0809 (3)	0.7518 (3)	0.4235 (2)	0.0799 (6)
H13A	−0.1104	0.8386	0.4398	0.120*
H13B	−0.0909	0.6793	0.5021	0.120*
H13C	−0.1549	0.7622	0.3639	0.120*
C14	0.1969 (2)	0.39882 (16)	0.79280 (14)	0.0423 (4)
C15	0.0804 (2)	0.39429 (19)	0.89627 (17)	0.0575 (5)
H15	−0.0092	0.4750	0.8975	0.069*
C16	0.0954 (3)	0.2717 (2)	0.99749 (19)	0.0686 (6)
H16	0.0167	0.2701	1.0665	0.082*
C17	0.2272 (3)	0.1519 (2)	0.99593 (19)	0.0678 (6)
H17	0.2381	0.0692	1.0643	0.081*
C18	0.3423 (3)	0.15430 (19)	0.89392 (19)	0.0637 (5)
H18	0.4300	0.0726	0.8925	0.076*
C19	0.3295 (2)	0.27597 (18)	0.79372 (17)	0.0531 (4)
H19	0.4099	0.2766	0.7258	0.064*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0522 (7)	0.0401 (7)	0.0579 (7)	−0.0079 (5)	0.0052 (5)	−0.0165 (5)
O2	0.0517 (6)	0.0357 (6)	0.0438 (6)	−0.0129 (5)	0.0106 (5)	−0.0134 (5)
O3	0.0540 (8)	0.0982 (11)	0.0823 (10)	−0.0365 (7)	0.0214 (7)	−0.0508 (9)
O4	0.0482 (7)	0.0722 (9)	0.0523 (7)	−0.0250 (6)	0.0004 (5)	−0.0241 (6)
C1	0.0431 (8)	0.0347 (8)	0.0416 (8)	−0.0115 (7)	−0.0013 (6)	−0.0111 (6)
C2	0.0481 (9)	0.0342 (8)	0.0390 (8)	−0.0142 (7)	0.0015 (7)	−0.0068 (6)
C3	0.0499 (9)	0.0437 (9)	0.0368 (8)	−0.0174 (7)	0.0050 (7)	−0.0129 (7)
C4	0.0528 (9)	0.0372 (8)	0.0431 (9)	−0.0126 (7)	0.0014 (7)	−0.0156 (7)
C5	0.0432 (8)	0.0351 (8)	0.0437 (9)	−0.0113 (6)	0.0007 (6)	−0.0145 (7)
C6	0.0498 (9)	0.0401 (9)	0.0508 (10)	−0.0178 (7)	0.0057 (7)	−0.0159 (7)
C7	0.0590 (12)	0.1008 (17)	0.0697 (13)	−0.0321 (12)	−0.0105 (10)	−0.0277 (12)
C8	0.0908 (18)	0.139 (2)	0.108 (2)	−0.0700 (17)	0.0064 (15)	−0.0615 (18)
C9	0.110 (2)	0.184 (3)	0.0641 (15)	−0.076 (2)	−0.0044 (14)	−0.0459 (18)
C10	0.094 (2)	0.116 (3)	0.146 (3)	0.0030 (18)	−0.057 (2)	−0.026 (2)
C11	0.0786 (13)	0.0560 (11)	0.0459 (10)	−0.0254 (9)	−0.0091 (9)	−0.0156 (8)
C12	0.133 (2)	0.0810 (16)	0.0502 (12)	−0.0445 (15)	−0.0187 (13)	−0.0041 (11)
C13	0.0670 (13)	0.1032 (18)	0.0811 (15)	−0.0288 (12)	−0.0189 (11)	−0.0356 (13)
C14	0.0498 (9)	0.0409 (9)	0.0378 (8)	−0.0173 (7)	−0.0034 (7)	−0.0123 (7)
C15	0.0672 (11)	0.0478 (10)	0.0471 (10)	−0.0165 (8)	0.0072 (8)	−0.0120 (8)
C16	0.0870 (14)	0.0654 (13)	0.0459 (10)	−0.0332 (11)	0.0097 (10)	−0.0086 (9)
C17	0.0943 (15)	0.0496 (11)	0.0497 (11)	−0.0275 (11)	−0.0122 (10)	0.0020 (8)
C18	0.0752 (13)	0.0427 (10)	0.0580 (12)	−0.0073 (9)	−0.0148 (10)	−0.0071 (8)
C19	0.0539 (10)	0.0487 (10)	0.0482 (10)	−0.0123 (8)	−0.0030 (8)	−0.0112 (8)

Geometric parameters (Å, º) top

O1—C1	1.1927 (18)	C9—H9C	0.9600
O2—C1	1.3584 (18)	C10—H10A	0.9600
O2—C5	1.4091 (17)	C10—H10B	0.9600
O3—C6	1.198 (2)	C10—H10C	0.9600
O4—C6	1.318 (2)	C11—C13	1.508 (3)
O4—C7	1.482 (2)	C11—C12	1.517 (3)
C1—C2	1.507 (2)	C11—H11	0.9800
C2—C6	1.523 (2)	C12—H12A	0.9600
C2—C3	1.542 (2)	C12—H12B	0.9600
C2—H2	0.9800	C12—H12C	0.9600
C3—C4	1.489 (2)	C13—H13A	0.9600
C3—C11	1.545 (2)	C13—H13B	0.9600
C3—H3	0.9800	C13—H13C	0.9600
C4—C5	1.320 (2)	C14—C15	1.386 (2)
C4—H4	0.9300	C14—C19	1.394 (2)
C5—C14	1.467 (2)	C15—C16	1.380 (3)
C7—C10	1.510 (4)	C15—H15	0.9300
C7—C8	1.512 (4)	C16—C17	1.375 (3)
C7—C9	1.513 (3)	C16—H16	0.9300
C8—H8A	0.9600	C17—C18	1.368 (3)
C8—H8B	0.9600	C17—H17	0.9300
C8—H8C	0.9600	C18—C19	1.370 (2)
C9—H9A	0.9600	C18—H18	0.9300
C9—H9B	0.9600	C19—H19	0.9300

C1—O2—C5	120.35 (11)	H9B—C9—H9C	109.5
C6—O4—C7	122.54 (14)	C7—C10—H10A	109.5
O1—C1—O2	117.45 (14)	C7—C10—H10B	109.5
O1—C1—C2	125.81 (14)	H10A—C10—H10B	109.5
O2—C1—C2	116.73 (12)	C7—C10—H10C	109.5
C1—C2—C6	109.81 (13)	H10A—C10—H10C	109.5
C1—C2—C3	112.32 (12)	H10B—C10—H10C	109.5
C6—C2—C3	109.70 (13)	C13—C11—C12	111.18 (19)
C1—C2—H2	108.3	C13—C11—C3	113.38 (15)
C6—C2—H2	108.3	C12—C11—C3	111.50 (16)
C3—C2—H2	108.3	C13—C11—H11	106.8
C4—C3—C2	107.53 (12)	C12—C11—H11	106.8
C4—C3—C11	112.76 (13)	C3—C11—H11	106.8
C2—C3—C11	115.19 (14)	C11—C12—H12A	109.5
C4—C3—H3	107.0	C11—C12—H12B	109.5
C2—C3—H3	107.0	H12A—C12—H12B	109.5
C11—C3—H3	107.0	C11—C12—H12C	109.5
C5—C4—C3	123.13 (14)	H12A—C12—H12C	109.5
C5—C4—H4	118.4	H12B—C12—H12C	109.5
C3—C4—H4	118.4	C11—C13—H13A	109.5
C4—C5—O2	121.22 (13)	C11—C13—H13B	109.5
C4—C5—C14	127.91 (14)	H13A—C13—H13B	109.5
O2—C5—C14	110.81 (12)	C11—C13—H13C	109.5
O3—C6—O4	126.45 (17)	H13A—C13—H13C	109.5
O3—C6—C2	122.48 (16)	H13B—C13—H13C	109.5
O4—C6—C2	111.06 (13)	C15—C14—C19	118.15 (15)
O4—C7—C10	108.8 (2)	C15—C14—C5	121.59 (15)
O4—C7—C8	109.19 (19)	C19—C14—C5	120.24 (14)
C10—C7—C8	113.0 (2)	C16—C15—C14	120.91 (17)
O4—C7—C9	101.57 (16)	C16—C15—H15	119.5
C10—C7—C9	111.9 (2)	C14—C15—H15	119.5
C8—C7—C9	111.7 (2)	C17—C16—C15	119.78 (19)
C7—C8—H8A	109.5	C17—C16—H16	120.1
C7—C8—H8B	109.5	C15—C16—H16	120.1
H8A—C8—H8B	109.5	C18—C17—C16	120.00 (17)
C7—C8—H8C	109.5	C18—C17—H17	120.0
H8A—C8—H8C	109.5	C16—C17—H17	120.0
H8B—C8—H8C	109.5	C17—C18—C19	120.62 (18)
C7—C9—H9A	109.5	C17—C18—H18	119.7
C7—C9—H9B	109.5	C19—C18—H18	119.7
H9A—C9—H9B	109.5	C18—C19—C14	120.52 (17)
C7—C9—H9C	109.5	C18—C19—H19	119.7
H9A—C9—H9C	109.5	C14—C19—H19	119.7

C5—O2—C1—O1	172.04 (14)	C3—C2—C6—O4	−134.60 (13)
C5—O2—C1—C2	−9.4 (2)	C6—O4—C7—C10	−61.0 (3)
O1—C1—C2—C6	97.55 (18)	C6—O4—C7—C8	62.8 (2)
O2—C1—C2—C6	−80.92 (16)	C6—O4—C7—C9	−179.16 (19)
O1—C1—C2—C3	−140.10 (16)	C4—C3—C11—C13	72.2 (2)
O2—C1—C2—C3	41.43 (19)	C2—C3—C11—C13	−51.7 (2)
C1—C2—C3—C4	−47.02 (17)	C4—C3—C11—C12	−161.41 (17)
C6—C2—C3—C4	75.39 (15)	C2—C3—C11—C12	74.6 (2)
C1—C2—C3—C11	79.62 (17)	C4—C5—C14—C15	−158.33 (18)
C6—C2—C3—C11	−157.96 (13)	O2—C5—C14—C15	18.9 (2)
C2—C3—C4—C5	25.9 (2)	C4—C5—C14—C19	20.1 (3)
C11—C3—C4—C5	−102.21 (19)	O2—C5—C14—C19	−162.68 (14)
C3—C4—C5—O2	5.5 (2)	C19—C14—C15—C16	0.2 (3)
C3—C4—C5—C14	−177.58 (15)	C5—C14—C15—C16	178.69 (17)
C1—O2—C5—C4	−15.6 (2)	C14—C15—C16—C17	−0.3 (3)
C1—O2—C5—C14	166.99 (13)	C15—C16—C17—C18	−0.4 (3)
C7—O4—C6—O3	−0.8 (3)	C16—C17—C18—C19	1.2 (3)
C7—O4—C6—C2	179.96 (15)	C17—C18—C19—C14	−1.3 (3)
C1—C2—C6—O3	170.02 (16)	C15—C14—C19—C18	0.6 (3)
C3—C2—C6—O3	46.1 (2)	C5—C14—C19—C18	−177.89 (16)
C1—C2—C6—O4	−10.70 (17)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O1ⁱ	0.98	2.44	3.407 (2)	170

Symmetry code: (i) −x, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₉H₂₄O₄
M_r	316.38
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	8.6163 (9), 10.888 (1), 11.261 (1)
α, β, γ (°)	68.393 (2), 79.118 (2), 67.998 (2)
V (Å³)	909.09 (15)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.48 × 0.46 × 0.42

Data collection
Diffractometer	Bruker SMART CCD area-detector
Absorption correction	Multi-scan (SADABS; Sheldrick, 2004)
T_min, T_max	0.760, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	4986, 3510, 2759
R_int	0.051
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.055, 0.158, 1.04
No. of reflections	3510
No. of parameters	213
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.21

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O1ⁱ	0.98	2.44	3.407 (2)	170.2

Symmetry code: (i) −x, −y+2, −z+1.

Acknowledgements

The authors thank the EPSRC for financial support.

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