Pseudosymmetric (E)-methyl 2-oxo-4-phenyl­but-3-enoate

The structure of the title compound, C₁₁H₁₀O₃, shows pseudo-symmetry. Since the mol­ecule is nearly planar and all non-H atoms lie close to an approximate mirror plane perpendicular to the crystallographic b axis, the structure could almost (85%) be described in space group P2₁/m. However, the correct space group is P2₁.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.047
• wR factor = 0.130
• Data-to-parameter ratio = 7.6

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT111_ALERT_2_B ADDSYM Detects (Pseudo) Centre of Symmetry .....         85 PerFi

Alert level C
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.63
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C3     -   C4     ...       1.55 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.56
           From the CIF: _reflns_number_total                977
           Count of symmetry unique reflns          983
           Completeness (_total/calc)             99.39%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Unsaturated α-ketoesters are of great synthetic interest and are widely used as substrates for enantioselective 1,4-additions. For example, Jensen et al. (2001) could develop an highly enantioselective Friedel-Crafts type addition of different electron rich arenes to (E)-methyl 2-oxo-4-phenylbut-3-enoate (Jensen et al., 2001; Jørgensen, 2003). The title compound, (I), was synthesized by an Lewis-Acid catalysed aldol condensation of benzaldehyde and methylpyruvate.

Geometric parameters of (I) are in the normal ranges. The C—C double bond is trans configured and the two carbonyl groups are also trans to each other (Fig. 1). The molecule is almost planar, the r.m.s. deviation for all non-H atoms being 0.208 Å. The structure of (I) shows pseudo-symmetry. The packing diagram (Fig. 2) reveals that the non-H atoms almost lie on a mirror plane perpendicular to the crystallographic b axis. A check for missed symmetry with PLATON (Spek, 2003) suggests space group P2₁/m with the higher symmetry being fulfilled by 85% of the atoms. However, the correct space group is P2₁.

Related literature

For related literature, see: Dujardin et al. (2001); Jørgensen (2003); Jensen et al. (2001); Spek (2003).

S2. Experimental

The title compound was synthesized by an Lewis-Acid catalysed aldol condensation of benzaldehyde and methylpyruvate (Dujardin et al., 2001).

S3. Refinement

In the absence of anomalous scatterers Friedel pairs had been merged prior to refinement. The absolute structure was arbitrarily assigned. H atoms were found in a difference map, but they were refined using a riding model with C—H = 0.95 Å and U_iso(H) = 1.2U_eq(C) or C—H = 0.98 Å and U_iso(H) = 1.5U_eq(C_methyl). The methyl group was allowed to rotate but not to tip.

Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Perspective view of (I) with the atom numbering. Displacement ellipsoids of non-H atoms are drawn at the 50% probability level.
	Fig. 2. Packing diagram of (I), viewed onto the bc plane.

(E)-Methyl 2-oxo-4-phenylbut-3-enoate

Crystal data

C11H10O3	F(000) = 200
Mr = 190.19	Dx = 1.311 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 5679 reflections
a = 7.1114 (10) Å	θ = 3.8–25.2°
b = 6.5381 (6) Å	µ = 0.10 mm^−1
c = 10.5106 (15) Å	T = 173 K
β = 99.527 (11)°	Plate, colourless
V = 481.95 (11) Å^3	0.34 × 0.31 × 0.22 mm
Z = 2

Data collection

Stoe IPDS II two-circle- diffractometer	937 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.035
Graphite monochromator	θmax = 25.6°, θmin = 3.7°
ω scans	h = −8→8
4453 measured reflections	k = −7→7
977 independent reflections	l = −12→12

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.130	H-atom parameters constrained
S = 1.19	w = 1/[σ^2(Fo^2) + (0.043P)^2 + 0.4561P] where P = (Fo^2 + 2Fc^2)/3
977 reflections	(Δ/σ)max < 0.001
128 parameters	Δρmax = 0.26 e Å^−3
1 restraint	Δρmin = −0.35 e Å^−3

Special details

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	0.6767 (5)	0.2097 (7)	0.2504 (3)	0.0233 (8)
H1	0.7866	0.1968	0.3149	0.028*
C2	0.5092 (5)	0.2322 (8)	0.2914 (3)	0.0242 (8)
H2	0.3959	0.2509	0.2305	0.029*
C3	0.4997 (5)	0.2281 (8)	0.4302 (3)	0.0257 (8)
O3	0.6377 (3)	0.2281 (8)	0.5165 (2)	0.0438 (9)
C4	0.2961 (5)	0.2250 (8)	0.4643 (3)	0.0244 (8)
O4	0.1529 (3)	0.2226 (8)	0.3846 (2)	0.0442 (9)
O5	0.3006 (3)	0.2202 (6)	0.5911 (2)	0.0286 (7)
C6	0.1147 (5)	0.2062 (10)	0.6332 (3)	0.0339 (10)
H6A	0.0452	0.3348	0.6139	0.051*
H6B	0.1333	0.1806	0.7263	0.051*
H6C	0.0414	0.0936	0.5876	0.051*
C11	0.7074 (5)	0.2029 (7)	0.1152 (3)	0.0229 (8)
C12	0.5656 (5)	0.2600 (6)	0.0122 (3)	0.0261 (9)
H12	0.4461	0.3088	0.0287	0.031*
C13	0.5998 (5)	0.2451 (8)	−0.1155 (3)	0.0303 (9)
H13	0.5044	0.2851	−0.1853	0.036*
C14	0.7741 (6)	0.1715 (6)	−0.1390 (4)	0.0309 (10)
H14	0.7969	0.1603	−0.2253	0.037*
C15	0.9150 (6)	0.1141 (8)	−0.0380 (4)	0.0323 (10)
H15	1.0338	0.0643	−0.0551	0.039*
C16	0.8823 (5)	0.1295 (7)	0.0884 (4)	0.0276 (9)
H16	0.9793	0.0899	0.1574	0.033*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0243 (15)	0.0251 (19)	0.0206 (15)	0.003 (2)	0.0041 (12)	−0.0008 (18)
C2	0.0222 (15)	0.031 (2)	0.0187 (15)	0.002 (2)	0.0009 (12)	−0.001 (2)
C3	0.0219 (15)	0.034 (2)	0.0210 (15)	0.001 (2)	0.0029 (12)	−0.002 (2)
O3	0.0215 (12)	0.087 (3)	0.0219 (12)	−0.003 (2)	−0.0003 (9)	−0.001 (2)
C4	0.0227 (15)	0.029 (2)	0.0222 (15)	0.002 (2)	0.0051 (12)	−0.003 (2)
O4	0.0223 (12)	0.081 (2)	0.0268 (13)	0.003 (2)	−0.0029 (10)	0.000 (2)
O5	0.0228 (11)	0.0454 (17)	0.0186 (11)	−0.0030 (18)	0.0068 (9)	−0.0006 (17)
C6	0.0232 (17)	0.053 (3)	0.0283 (18)	0.001 (2)	0.0117 (14)	0.002 (2)
C11	0.0257 (16)	0.023 (2)	0.0195 (16)	−0.0025 (19)	0.0037 (13)	0.0008 (18)
C12	0.0275 (17)	0.026 (2)	0.0246 (17)	0.0041 (18)	0.0037 (14)	0.0006 (17)
C13	0.0368 (19)	0.032 (2)	0.0209 (16)	0.000 (2)	0.0013 (14)	0.004 (2)
C14	0.040 (2)	0.031 (3)	0.0235 (17)	−0.0031 (19)	0.0114 (16)	−0.0015 (17)
C15	0.034 (2)	0.035 (2)	0.030 (2)	−0.001 (2)	0.0132 (17)	0.0004 (19)
C16	0.0253 (18)	0.030 (2)	0.0283 (19)	0.0013 (18)	0.0078 (15)	−0.0005 (18)

Geometric parameters (Å, º)

C1—C2	1.340 (5)	C6—H6C	0.9800
C1—C11	1.473 (4)	C11—C12	1.403 (5)
C1—H1	0.9500	C11—C16	1.405 (5)
C2—C3	1.472 (4)	C12—C13	1.407 (5)
C2—H2	0.9500	C12—H12	0.9500
C3—O3	1.221 (4)	C13—C14	1.389 (6)
C3—C4	1.548 (4)	C13—H13	0.9500
C4—O4	1.207 (4)	C14—C15	1.386 (6)
C4—O5	1.328 (4)	C14—H14	0.9500
O5—C6	1.464 (4)	C15—C16	1.390 (5)
C6—H6A	0.9800	C15—H15	0.9500
C6—H6B	0.9800	C16—H16	0.9500
C2—C1—C11	126.5 (3)	C12—C11—C16	118.9 (3)
C2—C1—H1	116.7	C12—C11—C1	122.3 (3)
C11—C1—H1	116.7	C16—C11—C1	118.8 (3)
C1—C2—C3	120.4 (3)	C11—C12—C13	120.2 (3)
C1—C2—H2	119.8	C11—C12—H12	119.9
C3—C2—H2	119.8	C13—C12—H12	119.9
O3—C3—C2	125.0 (3)	C14—C13—C12	119.6 (3)
O3—C3—C4	119.7 (3)	C14—C13—H13	120.2
C2—C3—C4	115.3 (3)	C12—C13—H13	120.2
O4—C4—O5	125.0 (3)	C15—C14—C13	120.7 (3)
O4—C4—C3	123.6 (3)	C15—C14—H14	119.6
O5—C4—C3	111.3 (3)	C13—C14—H14	119.6
C4—O5—C6	115.6 (3)	C14—C15—C16	119.9 (4)
O5—C6—H6A	109.5	C14—C15—H15	120.0
O5—C6—H6B	109.5	C16—C15—H15	120.0
H6A—C6—H6B	109.5	C15—C16—C11	120.7 (4)
O5—C6—H6C	109.5	C15—C16—H16	119.6
H6A—C6—H6C	109.5	C11—C16—H16	119.6
H6B—C6—H6C	109.5
C11—C1—C2—C3	177.6 (4)	C2—C1—C11—C16	−164.6 (5)
C1—C2—C3—O3	8.6 (9)	C16—C11—C12—C13	−0.5 (6)
C1—C2—C3—C4	−171.7 (4)	C1—C11—C12—C13	−178.1 (4)
O3—C3—C4—O4	−179.2 (7)	C11—C12—C13—C14	0.7 (7)
C2—C3—C4—O4	1.2 (7)	C12—C13—C14—C15	−0.5 (7)
O3—C3—C4—O5	−0.7 (7)	C13—C14—C15—C16	0.2 (7)
C2—C3—C4—O5	179.6 (5)	C14—C15—C16—C11	0.0 (7)
O4—C4—O5—C6	1.5 (8)	C12—C11—C16—C15	0.2 (6)
C3—C4—O5—C6	−176.9 (4)	C1—C11—C16—C15	177.9 (4)
C2—C1—C11—C12	12.9 (8)