Ethyl 1-acetyl-1H-indole-3-carboxyl­ate

Siddiquee, T.; Islam, S.; Bennett, D.; Zeller, M.; Hossain, M.

doi:10.1107/S1600536809025379

organic compounds

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ISSN: 2056-9890

Volume 65| Part 8| August 2009| Pages o1802-o1803

doi:10.1107/S1600536809025379

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Ethyl 1-acetyl-1H-indole-3-carboxylate

Tasneem Siddiquee,^a ^* Shahid Islam,^b Dennis Bennett,^b Matthias Zeller ^c and Mahmun Hossain ^b

^aDepartment of Chemistry, Boswell Science Complex, Tennessee State University, Nashville, 3500 John A Merritt Blvd, Nashville, TN 37209, USA, ^bDepartment of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, 3210 N Cramer Street, Milwaukee, WI 53211, USA, and ^cYoungstown State University, Department of Chemistry, One University Plaza, Youngstown Ohio 44555-3663, USA
^*Correspondence e-mail: tsiddiqu@tnstate.edu

(Received 11 June 2009; accepted 1 July 2009; online 8 July 2009)

The title compound, C₁₃H₁₃NO₃, was synthesized by acetylation of ethyl 1H-indole-3-carboxylate. The aromatic ring system of the molecule is essentially planar, but the saturated ethyl group is also located within this plane and the overall r.m.s. deviation from planarity is only 0.034 Å. Pairs of C—H⋯O interactions connect molecules into chains along the diagonal of the unit cell. Molecules also form weakly connected dimers via π⋯π stacking interactions of the indole rings with centroid–centroid separations of 3.571 (1) Å. C—H⋯π interactions between methylene and methyl groups and the indole and benzene ring complete the directional intermolecular interactions found in the crystal structure.

Related literature

For the biological properties of tryptophan derivatives, see: Ma et al. (2001 ); Zhou et al. (2006 ); Zhao, Smith et al. (2002 ); Zhao, Liao & Cook (2002 ). For synthetic procedures towards tryptophan-like compounds, see: Ager & Laneman (2004 ); Amir-Heidari et al. (2007 ); Carlier et al. (2002 ); Hengartner et al. (1979 ); Moriya et al. (1980 ). For the synthesis of 2-acetamido-3-ethoxy-3-oxopropanoic acid, see: Hellmann et al. (1958 ). For NMR data for the title compound, see: Reimann et al. (1990 ).

Experimental

Crystal data

C₁₃H₁₃NO₃
M_r = 231.24
Triclinic, $[P \overline 1]$
a = 7.519 (1) Å
b = 8.479 (1) Å
c = 10.187 (2) Å
α = 97.38 (1)°
β = 95.78 (2)°
γ = 114.28 (1)°
V = 578.58 (15) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 296 K
0.51 × 0.41 × 0.20 mm

Data collection

Siemens P4 diffractometer
Absorption correction: multi-scan [XSCANS (Siemens, 1996 ) and XPREP (Siemens, 1994 )] T_min = 0.823, T_max = 0.981
2536 measured reflections
2027 independent reflections
1696 reflections with I > 2σ(I)
R_int = 0.019
3 standard reflections every 97 reflections intensity decay: <1%

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.120
S = 1.09
2027 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯O3ⁱ	0.93	2.61	3.296 (2)	131
C5—H5⋯O1ⁱⁱ	0.93	2.64	3.273 (2)	125
C12—H12B⋯Cg1ⁱⁱⁱ	0.96	2.95	3.618 (3)	127
C13—H13B⋯Cg2ⁱⁱⁱ	0.96	2.78	3.587 (3)	142
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) -x, -y+1, -z+2; (iii) -x, -y+2, -z+2. Cg1 is the centroid of the N1,C1,C6–C8 pyrrole ring and Cg2 is the centroid of the C1–C6 phenyl ring.

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: XPREP (Siemens 1994) and SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809025379/bh2233sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809025379/bh2233Isup2.hkl

checkCIF report

Comment top

Indole substituted at 3-position leads to variety of compounds that are precursors to biologically active important alkaloids. One of the most important compounds of this type is tryptophan, which possesses anticancerous, antimalarial, antiamoebic, and antihypertensive activities (Ma et al., 2001; Zhou et al., 2006; Zhao, Smith et al. 2002; Zhao, Liao, & Cook, 2002). α,β-Dehydroaminoacid esters (e.g. 1, Fig. 1) are precursors to synthesizing tryptophan derivatives, which upon hydrogenation yield optically active tryptophan and its analogues (Ager & Laneman, 2004).

α,β-Dehydroamino acid esters were also synthesized using Erlenmeyer condensation (Amir-Heidari et al., 2007), Schmidt olefinations (Carlier et al., 2002), condensation of indole aldehyde with acetylamino malonic acid ester (Hengartner et al., 1979), and Knoevenagel-type condensation (Moriya et al. 1980). One such effort to synthesize hydroxyl dehydrotryptophan (3) from indoleester (1) using mono acid malonic ester (2) and aceticanhydride-pyridine mixture (Fig. 1) proved to be unsuccessful. The reaction resulted in 1H-indole-3-carboxylic acid-N-acetylethyl ester (4) instead. We rationalize that it is the electron withdrawing effect of the ester group which increases the acidity of the molecule. Consequently, in presence of a base, like pyridine, deprotonation and introduction of an acylium ion may occur. In this article we report the crystal structure of this compound.

The structure of the title compound is shown in Figure 2. The aromatic ring system of the molecule is essentially planar, but also the saturated ethyl group is located within this plane and the overall r.m.s. deviation from planarity is only 0.034 Å. Pairs of C—H···O interactions connect molecules into chains along the diagonal of the unit cell (Fig. 3). Molecules form weakly connected dimers via π···π stacking interactions of the indole rings with centroid to centroid distances of 3.571 (1) Å [symmetry operator for the second indole ring: (iii) 1 - x, 2 - y, 2 - z]. C—H···π interactions between methylene and methyl groups and the indole and benzene ring complete the range of intermolecular interactions [C12—H12B···Cg1ⁱⁱⁱ = 2.95 Å, X—H···Cg1ⁱⁱⁱ = 127°, X···Cg1ⁱⁱⁱ = 3.618 (3) Å; C13—H13B···Cg2ⁱⁱⁱ = 2.78 Å, X—H···Cg2ⁱⁱⁱ = 142°, X···Cg2ⁱⁱⁱ = 3.587 (3) Å; Cg1 and Cg2 are the centroids of the indole and the benzene rings, respectively].

Related literature top

For the biological properties of tryptophan derivatives, see: Ma et al. (2001); Zhou et al. (2006); Zhao, Smith et al. (2002); Zhao, Liao & Cook (2002) . For synthetic procedures towards tryptophan-like compounds, see: Ager & Laneman (2004); Amir-Heidari et al. (2007); Carlier et al. (2002); Hengartner et al. (1979); Moriya et al. (1980). For the synthesis of 2-acetamido-3-ethoxy-3-oxopropanoic acid, see: Hellmann et al. (1958). For NMR data for the title compound, see: Reimann et al. (1990).

Experimental top

2-Acetamido-3-ethoxy-3-oxopropanoic acid (one of the starting materials) was prepared from acetylamino malonic acid diethylester following the process developed by Hellmann et al. (1958). The title compound was prepared as follows: to a mixture of 0.37 g (1.97 mmol) of the indole ester ethyl 1H-indole-3-carboxylate, 1.1 g (5.9 mmol) of 2-acetamido-3-ethoxy-3-oxopropanoic acid, and 4.54 ml of pyridine was added at 288 K (15 °C) over 15 minutes 1.6 ml of acetic anhydride. The reaction mixture turned yellow and was stirred at 333 K (60 °C) for 3 h. An additional 0.18 g (0.9 mmol) of ethyl acetamido malonate was added and stirring was continued for 22 h. Ice (10 ml) was added, and the mixture was stirred for 2 h and then diluted with 20 ml of water. The resulting solution was extracted with EtOAc (2 × 20 ml), the combined organic layer was dried with anhydrous Na₂SO₄ and the solvent was removed under reduced pressure. 0.4 g (99%) of 1H-indole-3-carboxylicacid-N-acetyl ethyl ester was isolated. ¹HNMR CDCl₃ δ (p.p.m.): 8.70–8.50 (m,1H and 2H), 7.60–7.30 (m, 2H), 4.45 (q, J = 7 Hz, OCH₂CH₃), 2.70 (s, COCH₃), 1.45 (t, J = 7 Hz, OCH₂CH₃). The NMR data agree with those reported previously (Reimann et al., 1990). Crystals suitable for X-ray structural analysis were obtained by recrystallization form ethanol in a refrigerator.

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: XPREP (Siemens 1994) and SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Synthesis of the title compound (4).
	Fig. 2. Thermal ellipsoid plot of the title compound with the atom labeling scheme. Displacement ellipsoids are shown at the 50% probability level and H atoms are shown as capped sticks.
	Fig. 3. Packing view of the title compound showing C—H···O interactions (blue lines).

Ethyl 1-acetyl-1H-indole-3-carboxylate top

Crystal data top

C₁₃H₁₃NO₃	Z = 2
M_r = 231.24	F(000) = 244
Triclinic, P1	D_x = 1.327 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.519 (1) Å	Cell parameters from 23 reflections
b = 8.479 (1) Å	θ = 3.7–11.4°
c = 10.187 (2) Å	µ = 0.10 mm⁻¹
α = 97.38 (1)°	T = 296 K
β = 95.78 (2)°	Block, colourless
γ = 114.28 (1)°	0.51 × 0.41 × 0.20 mm
V = 578.58 (15) Å³

Data collection top

Siemens P4 diffractometer	1696 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.019
Graphite monochromator	θ_max = 25.0°, θ_min = 2.1°
2θ/ω scans	h = −8→1
Absorption correction: multi-scan [XSCANS (Siemens 1996) and XPREP (Siemens, 1994)]	k = −9→9
T_min = 0.823, T_max = 0.981	l = −12→12
2536 measured reflections	3 standard reflections every 97 reflections
2027 independent reflections	intensity decay: <1%

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H-atom parameters constrained
wR(F²) = 0.120	w = 1/[σ²(F_o²) + (0.0647P)² + 0.0738P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max = 0.001
2027 reflections	Δρ_max = 0.17 e Å⁻³
155 parameters	Δρ_min = −0.18 e Å⁻³
0 restraints	Extinction correction: SHELXTL (Bruker, 2003; Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 constraints	Extinction coefficient: 0.103 (12)
Primary atom site location: structure-invariant direct methods

Crystal data top

C₁₃H₁₃NO₃	γ = 114.28 (1)°
M_r = 231.24	V = 578.58 (15) Å³
Triclinic, P1	Z = 2
a = 7.519 (1) Å	Mo Kα radiation
b = 8.479 (1) Å	µ = 0.10 mm⁻¹
c = 10.187 (2) Å	T = 296 K
α = 97.38 (1)°	0.51 × 0.41 × 0.20 mm
β = 95.78 (2)°

Data collection top

Siemens P4 diffractometer	1696 reflections with I > 2σ(I)
Absorption correction: multi-scan [XSCANS (Siemens 1996) and XPREP (Siemens, 1994)]	R_int = 0.019
T_min = 0.823, T_max = 0.981	3 standard reflections every 97 reflections
2536 measured reflections	intensity decay: <1%
2027 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.120	H-atom parameters constrained
S = 1.09	Δρ_max = 0.17 e Å⁻³
2027 reflections	Δρ_min = −0.18 e Å⁻³
155 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.3179 (2)	0.9158 (2)	0.76860 (15)	0.0474 (4)
C2	0.3276 (2)	0.8319 (2)	0.64495 (16)	0.0560 (4)
H2	0.3926	0.8952	0.5826	0.067*
C3	0.2364 (3)	0.6502 (2)	0.61896 (18)	0.0641 (5)
H3	0.2402	0.5898	0.5371	0.077*
C4	0.1394 (3)	0.5554 (2)	0.71141 (19)	0.0658 (5)
H4	0.0804	0.4330	0.6907	0.079*
C5	0.1286 (3)	0.6392 (2)	0.83389 (17)	0.0572 (4)
H5	0.0629	0.5747	0.8955	0.069*
C6	0.2186 (2)	0.8227 (2)	0.86285 (15)	0.0477 (4)
C7	0.2359 (2)	0.9517 (2)	0.97738 (15)	0.0477 (4)
C8	0.3421 (2)	1.1130 (2)	0.95024 (15)	0.0491 (4)
H8	0.3747	1.2189	1.0077	0.059*
C9	0.1539 (2)	0.9133 (2)	1.10037 (16)	0.0526 (4)
C10	0.5038 (3)	1.2371 (2)	0.76197 (16)	0.0563 (4)
C11	0.5648 (3)	1.4194 (3)	0.8383 (2)	0.0756 (6)
H11A	0.6392	1.4336	0.9248	0.113*
H11B	0.4491	1.4377	0.8497	0.113*
H11C	0.6452	1.5037	0.7894	0.113*
C12	0.1351 (3)	1.0333 (3)	1.31867 (17)	0.0613 (5)
H12A	0.1950	0.9683	1.3634	0.074*
H12B	−0.0076	0.9667	1.3045	0.074*
C13	0.1950 (3)	1.2107 (3)	1.40273 (18)	0.0724 (5)
H13A	0.1508	1.1970	1.4875	0.109*
H13B	0.1361	1.2743	1.3572	0.109*
H13C	0.3366	1.2747	1.4175	0.109*
N1	0.39555 (19)	1.09788 (17)	0.82406 (12)	0.0489 (4)
O1	0.0559 (3)	0.76795 (18)	1.11828 (14)	0.0845 (5)
O2	0.20161 (17)	1.05915 (15)	1.19112 (11)	0.0559 (3)
O3	0.5434 (2)	1.20764 (19)	0.65295 (13)	0.0814 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0485 (8)	0.0506 (9)	0.0420 (8)	0.0226 (7)	0.0046 (6)	0.0028 (6)
C2	0.0594 (10)	0.0612 (10)	0.0452 (9)	0.0262 (8)	0.0100 (7)	0.0006 (7)
C3	0.0707 (11)	0.0617 (11)	0.0531 (10)	0.0282 (9)	0.0083 (8)	−0.0092 (8)
C4	0.0744 (11)	0.0493 (10)	0.0660 (11)	0.0245 (9)	0.0072 (9)	−0.0049 (8)
C5	0.0631 (10)	0.0494 (9)	0.0552 (10)	0.0216 (8)	0.0084 (8)	0.0070 (7)
C6	0.0492 (8)	0.0497 (8)	0.0437 (8)	0.0231 (7)	0.0043 (6)	0.0036 (7)
C7	0.0521 (8)	0.0502 (9)	0.0419 (8)	0.0239 (7)	0.0077 (6)	0.0062 (7)
C8	0.0569 (9)	0.0503 (9)	0.0405 (8)	0.0245 (7)	0.0102 (6)	0.0032 (6)
C9	0.0617 (9)	0.0541 (10)	0.0467 (9)	0.0283 (8)	0.0122 (7)	0.0108 (7)
C10	0.0656 (10)	0.0570 (10)	0.0478 (9)	0.0254 (8)	0.0155 (7)	0.0131 (7)
C11	0.0980 (15)	0.0525 (11)	0.0726 (12)	0.0247 (10)	0.0284 (11)	0.0146 (9)
C12	0.0718 (11)	0.0789 (12)	0.0442 (9)	0.0395 (10)	0.0208 (8)	0.0160 (8)
C13	0.0812 (13)	0.0925 (14)	0.0491 (10)	0.0451 (11)	0.0156 (9)	0.0023 (9)
N1	0.0562 (8)	0.0484 (7)	0.0406 (7)	0.0215 (6)	0.0105 (5)	0.0044 (5)
O1	0.1286 (12)	0.0546 (8)	0.0692 (9)	0.0304 (8)	0.0424 (8)	0.0197 (6)
O2	0.0660 (7)	0.0586 (7)	0.0430 (6)	0.0256 (6)	0.0172 (5)	0.0069 (5)
O3	0.1158 (11)	0.0731 (9)	0.0556 (8)	0.0346 (8)	0.0377 (7)	0.0162 (7)

Geometric parameters (Å, º) top

C1—C2	1.389 (2)	C9—O1	1.197 (2)
C1—C6	1.399 (2)	C9—O2	1.3367 (19)
C1—N1	1.4186 (19)	C10—O3	1.201 (2)
C2—C3	1.379 (2)	C10—N1	1.400 (2)
C2—H2	0.9300	C10—C11	1.497 (3)
C3—C4	1.384 (3)	C11—H11A	0.9600
C3—H3	0.9300	C11—H11B	0.9600
C4—C5	1.381 (2)	C11—H11C	0.9600
C4—H4	0.9300	C12—O2	1.449 (2)
C5—C6	1.393 (2)	C12—C13	1.494 (3)
C5—H5	0.9300	C12—H12A	0.9700
C6—C7	1.449 (2)	C12—H12B	0.9700
C7—C8	1.352 (2)	C13—H13A	0.9600
C7—C9	1.467 (2)	C13—H13B	0.9600
C8—N1	1.391 (2)	C13—H13C	0.9600
C8—H8	0.9300

C2—C1—C6	122.32 (15)	O2—C9—C7	112.43 (14)
C2—C1—N1	130.20 (15)	O3—C10—N1	120.26 (16)
C6—C1—N1	107.48 (13)	O3—C10—C11	123.11 (16)
C3—C2—C1	116.89 (17)	N1—C10—C11	116.63 (15)
C3—C2—H2	121.6	C10—C11—H11A	109.5
C1—C2—H2	121.6	C10—C11—H11B	109.5
C2—C3—C4	121.75 (17)	H11A—C11—H11B	109.5
C2—C3—H3	119.1	C10—C11—H11C	109.5
C4—C3—H3	119.1	H11A—C11—H11C	109.5
C5—C4—C3	121.27 (17)	H11B—C11—H11C	109.5
C5—C4—H4	119.4	O2—C12—C13	107.88 (15)
C3—C4—H4	119.4	O2—C12—H12A	110.1
C4—C5—C6	118.33 (17)	C13—C12—H12A	110.1
C4—C5—H5	120.8	O2—C12—H12B	110.1
C6—C5—H5	120.8	C13—C12—H12B	110.1
C5—C6—C1	119.44 (14)	H12A—C12—H12B	108.4
C5—C6—C7	133.47 (15)	C12—C13—H13A	109.5
C1—C6—C7	107.10 (14)	C12—C13—H13B	109.5
C8—C7—C6	107.50 (14)	H13A—C13—H13B	109.5
C8—C7—C9	126.52 (15)	C12—C13—H13C	109.5
C6—C7—C9	125.98 (15)	H13A—C13—H13C	109.5
C7—C8—N1	110.33 (14)	H13B—C13—H13C	109.5
C7—C8—H8	124.8	C8—N1—C10	126.27 (14)
N1—C8—H8	124.8	C8—N1—C1	107.60 (13)
O1—C9—O2	123.51 (15)	C10—N1—C1	126.12 (13)
O1—C9—C7	124.06 (16)	C9—O2—C12	116.25 (13)

C6—C1—C2—C3	−0.9 (2)	C8—C7—C9—O1	177.82 (17)
N1—C1—C2—C3	−179.95 (15)	C6—C7—C9—O1	−2.6 (3)
C1—C2—C3—C4	0.1 (3)	C8—C7—C9—O2	−2.5 (2)
C2—C3—C4—C5	0.5 (3)	C6—C7—C9—O2	177.09 (13)
C3—C4—C5—C6	−0.2 (3)	C7—C8—N1—C10	179.14 (15)
C4—C5—C6—C1	−0.6 (2)	C7—C8—N1—C1	0.04 (17)
C4—C5—C6—C7	179.54 (17)	O3—C10—N1—C8	179.02 (16)
C2—C1—C6—C5	1.2 (2)	C11—C10—N1—C8	−1.0 (3)
N1—C1—C6—C5	−179.57 (13)	O3—C10—N1—C1	−2.1 (3)
C2—C1—C6—C7	−178.95 (14)	C11—C10—N1—C1	177.96 (15)
N1—C1—C6—C7	0.31 (16)	C2—C1—N1—C8	178.95 (16)
C5—C6—C7—C8	179.58 (17)	C6—C1—N1—C8	−0.23 (16)
C1—C6—C7—C8	−0.29 (17)	C2—C1—N1—C10	−0.1 (3)
C5—C6—C7—C9	0.0 (3)	C6—C1—N1—C10	−179.32 (15)
C1—C6—C7—C9	−179.90 (14)	O1—C9—O2—C12	2.7 (2)
C6—C7—C8—N1	0.15 (18)	C7—C9—O2—C12	−177.03 (13)
C9—C7—C8—N1	179.76 (14)	C13—C12—O2—C9	−177.54 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O3ⁱ	0.93	2.61	3.296 (2)	131
C5—H5···O1ⁱⁱ	0.93	2.64	3.273 (2)	125
C12—H12B···Cg1ⁱⁱⁱ	0.96	2.95	3.618 (3)	127
C13—H13B···Cg2ⁱⁱⁱ	0.96	2.78	3.587 (3)	142

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

Experimental details

Crystal data
Chemical formula	C₁₃H₁₃NO₃
M_r	231.24
Crystal system, space group	Triclinic, P1
Temperature (K)	296
a, b, c (Å)	7.519 (1), 8.479 (1), 10.187 (2)
α, β, γ (°)	97.38 (1), 95.78 (2), 114.28 (1)
V (Å³)	578.58 (15)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.51 × 0.41 × 0.20

Data collection
Diffractometer	Siemens P4 diffractometer
Absorption correction	Multi-scan [XSCANS (Siemens 1996) and XPREP (Siemens, 1994)]
T_min, T_max	0.823, 0.981
No. of measured, independent and observed [I > 2σ(I)] reflections	2536, 2027, 1696
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.120, 1.09
No. of reflections	2027
No. of parameters	155
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.18

Computer programs: XSCANS (Siemens, 1996), XPREP (Siemens 1994) and SHELXTL (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O3ⁱ	0.93	2.61	3.296 (2)	131
C5—H5···O1ⁱⁱ	0.93	2.64	3.273 (2)	125
C12—H12B···Cg1ⁱⁱⁱ	0.96	2.95	3.618 (3)	127
C13—H13B···Cg2ⁱⁱⁱ	0.96	2.78	3.587 (3)	142

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

Acknowledgements

TAS acknowledges the College of Arts and Science at TSU for release time.

References

Ager, D. J. & Laneman, S. (2004). Asymmetric Catalysis on Industrial Scale: Challenges, Approaches and Solutions, edited by H. U. Blaser & E. Schmidt, p. 30. Weinheim: WILEY-VCH Verlag GmbH & Co KGaA. Google Scholar
Amir-Heidari, B., Thirlway, J. & Micklefield, J. (2007). Org. Lett. 9, 1513–1516. Web of Science CrossRef PubMed CAS Google Scholar
Carlier, P. R., Lam, P. C.-H. & Wong, D. M. (2002). J. Org. Chem. 67, 6256–6259. Web of Science CrossRef PubMed CAS Google Scholar
Hellmann, H., Teichmann, K. & Lingens, F. (1958). Chem. Ber. 91, 2427–2431. CrossRef CAS Web of Science Google Scholar
Hengartner, U., Valentine, D. Jr, Johnson, K. K., Larscheid, M. E., Pigott, F., Scheidl, F., Scott, J. W., Sun, R. C., Townsend, J. M. & Williams, T. H. (1979). J. Org. Chem. 44, 3741–3747. CrossRef CAS Web of Science Google Scholar
Ma, C., Liu, X., Li, X., Flippen-Anderson, J., Yu, S. & Cook, J. M. (2001). J. Org. Chem. 66, 4525–4542. Web of Science CSD CrossRef PubMed CAS Google Scholar
Moriya, T., Hagio, K. & Yoneda, N. (1980). Chem. Pharm. Bull. 28, 1711–1721. CrossRef CAS Google Scholar
Reimann, E., Hassler, T. & Lotter, H. (1990). Arch. Pharm. 323, 255–258. CrossRef CAS Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Siemens (1994). XPREP. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Google Scholar
Siemens (1996). XSCANS. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Google Scholar
Zhao, S., Liao, X. & Cook, J. M. (2002). Org. Lett. 4, 687–690. Web of Science CrossRef PubMed CAS Google Scholar
Zhao, S., Smith, K. S., Deveau, A. M., Dieckhaus, C. M., Johnson, M. A., Macdonald, T. L. & Cook, J. M. (2002). J. Med. Chem. 45, 1559–1562. Web of Science CrossRef PubMed CAS Google Scholar
Zhou, H., Liao, X., Yin, W., Ma, J. & Cook, J. M. (2006). J. Org. Chem. 71, 251–259. Web of Science CrossRef PubMed CAS Google Scholar