(2E,5E)-2,5-Bis(2-bromo­benzyl­idene)­cyclo­penta­none

In the biologically active title compound, C₁₉H₁₄Br₂O, a derivative of curcumin, the dihedral angle between the aromatic ring planes is 59.78 (19)°.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.037
• wR factor = 0.095
• Data-to-parameter ratio = 14.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  O1      ..       3.14 Ang.

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

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

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S1. Comment

The title compound, (2E, 5E)-2,5-bis(2-bromobenzylidene) cyclopentanone, (I), derived from curcumin, is a biologically active compound. Curcumin has been found to possess a variety of pharmaceutical applications, for example, inhibiting carcinogen-induced mutations and the formation of tumour, antioxidation, anti-inflammation, anti-virus, decreasing total cholesterol and LDL cholesterol level (Began et al., 1999; Kawamon et al., 1999; Poorichaya et al., 2007). However, curcumin is unstable at a pH over 6.5, due to the presence of the methylene group. Omitting the methylene group and one carbonyl group, therefore, some mono-carbonyl curcumin analogues without the central methylene functional groups, were synthesized and their biological activity in vitro were evaluated. Part of bisbenzylidene cyclopentanone derivatives showed stronger bio-activity than curcumin (Artico et al., 1998; Butcher et al., 2007; Subbagh et al., 2000). The crystal structure of 2,5-bis(3,4-dimethoxybenzylidene) cyclopentanone (Butcher et al., 2007) has been reported. As part of our research in this area, we synthesized the title compound C₁₉H₁₄Br₂O and describe its structure here. Its geometrical parameters are normal; the dihedral angle between the aromatic ring planes is 59.78 (19)°.

Related literature

For related literature, see: Artico et al. (1998); Began et al. (1999); Butcher, Jasinski, Narayana et al. (2007); Butcher, Jasinski, Sarojini et al. (2007); Kawamori et al. (1999); Poorichaya et al. (2007); Subbagh et al. (2000).

S2. Experimental

To a solution of 15 mmol 2-bromobenzaldehyde in MeOH (10 ml) was added 7.5 mmol cyclopentanone. The solution was stirred at room temperature for 20 min, followed by added dropwise 20% (w/v) NaOH (1.5 ml, 7.5 mmol). The mixture was stirred at RT and monitored with TLC. When the reaction finished, the residue was poured into saturated NH₄Cl solution and filtered. The precipitate was washed and purified by chromatography over silica gel using CH₂Cl₂/CH₃OH as the eluent to afford the pure product (yield: 65%). Single crystals of (I) were grown in a CH₂Cl₂–CH₃OH mixture (8:2 v/v) by slow evaporation (mp 436–437 K). 1H-NMR (CDCl₃): 1.93 (4H, s, CH2—CH2), 7.23 (2H, m, Ar—H6), 7.37 (2H, m, Ar—H4), 7.52 (2H, m, Ar—H5), 7.66 (2H, m, Ar—H3), 7.86 (2H, s, Ar—CH=C2). ESI-MS m/z: 418.94 (M+1)+, calcd for C₁₉H₁₄Br₂O: 418.12.

S3. Refinement

The H atoms were positioned geometrically (C—H = 0.93–0.97 Å) and refined as riding with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C).

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2002); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of (I) shoiwng 30% displacement ellipsoids for the non-hydrogen atoms.

(2E,5E)-2,5-Bis(2-bromobenzylidene)cyclopentanone

Crystal data

C19H14Br2O	F(000) = 824
Mr = 418.12	Dx = 1.714 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2746 reflections
a = 8.6504 (8) Å	θ = 2.5–24.8°
b = 8.4789 (8) Å	µ = 5.00 mm^−1
c = 22.126 (2) Å	T = 298 K
β = 93.119 (2)°	Block, colourless
V = 1620.5 (3) Å^3	0.33 × 0.20 × 0.19 mm
Z = 4

Data collection

Bruker APEX CCD area-detector diffractometer	2857 independent reflections
Radiation source: fine-focus sealed tube	2292 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
φ and ω scans	θmax = 25.0°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −10→10
Tmin = 0.309, Tmax = 0.391	k = −10→9
8202 measured reflections	l = −26→21

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.095	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0424P)^2 + 1.7145P] where P = (Fo^2 + 2Fc^2)/3
2857 reflections	(Δ/σ)max = 0.001
199 parameters	Δρmax = 0.69 e Å^−3
0 restraints	Δρmin = −0.96 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
Br1	0.33176 (5)	0.34999 (5)	1.049559 (18)	0.05462 (16)
Br2	1.11065 (5)	0.18597 (7)	0.77243 (3)	0.0767 (2)
O1	0.6144 (3)	0.3500 (3)	0.86877 (12)	0.0550 (7)
C1	0.2692 (4)	0.1396 (4)	1.02839 (17)	0.0432 (8)
C2	0.3168 (4)	0.0684 (4)	0.97524 (16)	0.0410 (8)
C3	0.2662 (4)	−0.0868 (5)	0.96568 (17)	0.0505 (9)
H3	0.2942	−0.1396	0.9311	0.061*
C4	0.1760 (5)	−0.1643 (5)	1.00582 (19)	0.0575 (11)
H4	0.1448	−0.2677	0.9982	0.069*
C5	0.1322 (5)	−0.0883 (5)	1.05707 (19)	0.0565 (11)
H5	0.0708	−0.1403	1.0840	0.068*
C6	0.1786 (4)	0.0636 (5)	1.06871 (17)	0.0501 (10)
H6	0.1494	0.1150	1.1034	0.060*
C7	0.4145 (4)	0.1517 (4)	0.93415 (16)	0.0421 (8)
H7	0.4464	0.2509	0.9477	0.050*
C8	0.4664 (4)	0.1114 (4)	0.88048 (16)	0.0389 (8)
C9	0.5734 (4)	0.2199 (4)	0.85095 (15)	0.0395 (8)
C10	0.6236 (4)	0.1421 (4)	0.79538 (15)	0.0370 (8)
C11	0.5245 (5)	−0.0008 (5)	0.78286 (17)	0.0502 (9)
H11A	0.5873	−0.0898	0.7717	0.060*
H11B	0.4477	0.0199	0.7502	0.060*
C12	0.4453 (4)	−0.0347 (4)	0.84245 (16)	0.0431 (8)
H12A	0.3362	−0.0569	0.8343	0.052*
H12B	0.4931	−0.1248	0.8630	0.052*
C13	0.7469 (4)	0.1931 (4)	0.76776 (16)	0.0405 (8)
H13	0.7969	0.2809	0.7847	0.049*
C14	0.8131 (4)	0.1269 (4)	0.71370 (16)	0.0398 (8)
C15	0.9727 (4)	0.1184 (4)	0.70760 (18)	0.0479 (9)
C16	1.0353 (5)	0.0583 (5)	0.6568 (2)	0.0603 (11)
H16	1.1422	0.0531	0.6542	0.072*
C17	0.9385 (6)	0.0059 (5)	0.6099 (2)	0.0696 (14)
H17	0.9801	−0.0346	0.5752	0.083*
C18	0.7796 (6)	0.0129 (5)	0.61369 (19)	0.0634 (12)
H18	0.7143	−0.0213	0.5815	0.076*
C19	0.7185 (5)	0.0710 (5)	0.66541 (16)	0.0504 (10)
H19	0.6116	0.0730	0.6682	0.060*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0688 (3)	0.0473 (2)	0.0492 (2)	0.00208 (19)	0.01663 (19)	−0.00735 (18)
Br2	0.0447 (3)	0.0869 (4)	0.0983 (4)	0.0006 (2)	0.0019 (2)	−0.0170 (3)
O1	0.0654 (18)	0.0410 (16)	0.0605 (17)	−0.0107 (13)	0.0218 (14)	−0.0135 (13)
C1	0.0397 (19)	0.044 (2)	0.046 (2)	0.0049 (17)	0.0023 (16)	−0.0012 (16)
C2	0.0358 (19)	0.045 (2)	0.0428 (19)	0.0014 (16)	0.0020 (15)	0.0018 (16)
C3	0.052 (2)	0.052 (2)	0.048 (2)	−0.005 (2)	0.0111 (18)	−0.0045 (18)
C4	0.060 (3)	0.055 (3)	0.059 (3)	−0.012 (2)	0.008 (2)	−0.002 (2)
C5	0.047 (2)	0.064 (3)	0.060 (3)	−0.009 (2)	0.0128 (19)	0.014 (2)
C6	0.044 (2)	0.061 (3)	0.046 (2)	0.0028 (19)	0.0086 (17)	0.0020 (19)
C7	0.0402 (19)	0.0360 (19)	0.050 (2)	0.0002 (16)	0.0062 (16)	−0.0028 (16)
C8	0.0357 (18)	0.0379 (19)	0.043 (2)	0.0024 (15)	0.0042 (15)	−0.0032 (15)
C9	0.0398 (19)	0.039 (2)	0.0397 (19)	0.0021 (16)	0.0039 (15)	−0.0032 (16)
C10	0.0344 (18)	0.0375 (19)	0.0394 (18)	0.0031 (15)	0.0039 (14)	−0.0026 (15)
C11	0.050 (2)	0.050 (2)	0.051 (2)	−0.0075 (19)	0.0114 (17)	−0.0139 (18)
C12	0.043 (2)	0.042 (2)	0.045 (2)	−0.0052 (16)	0.0040 (16)	−0.0075 (16)
C13	0.043 (2)	0.0348 (19)	0.0439 (19)	0.0020 (16)	0.0032 (16)	−0.0042 (15)
C14	0.044 (2)	0.0315 (18)	0.045 (2)	0.0043 (16)	0.0082 (16)	0.0014 (15)
C15	0.048 (2)	0.037 (2)	0.060 (2)	0.0021 (17)	0.0161 (18)	0.0045 (17)
C16	0.068 (3)	0.048 (3)	0.068 (3)	0.007 (2)	0.033 (2)	0.008 (2)
C17	0.104 (4)	0.052 (3)	0.056 (3)	0.009 (3)	0.042 (3)	0.001 (2)
C18	0.098 (4)	0.048 (3)	0.045 (2)	−0.006 (2)	0.012 (2)	−0.0036 (19)
C19	0.057 (2)	0.046 (2)	0.049 (2)	0.0000 (19)	0.0094 (19)	0.0020 (18)

Geometric parameters (Å, º)

Br1—C1	1.915 (4)	C10—C13	1.330 (5)
Br2—C15	1.904 (4)	C10—C11	1.501 (5)
O1—C9	1.217 (4)	C11—C12	1.545 (5)
C1—C6	1.379 (5)	C11—H11A	0.9700
C1—C2	1.403 (5)	C11—H11B	0.9700
C2—C3	1.400 (5)	C12—H12A	0.9700
C2—C7	1.457 (5)	C12—H12B	0.9700
C3—C4	1.380 (6)	C13—C14	1.466 (5)
C3—H3	0.9300	C13—H13	0.9300
C4—C5	1.375 (6)	C14—C19	1.393 (5)
C4—H4	0.9300	C14—C15	1.396 (5)
C5—C6	1.369 (6)	C15—C16	1.372 (5)
C5—H5	0.9300	C16—C17	1.372 (7)
C6—H6	0.9300	C16—H16	0.9300
C7—C8	1.337 (5)	C17—C18	1.384 (7)
C7—H7	0.9300	C17—H17	0.9300
C8—C9	1.482 (5)	C18—C19	1.377 (5)
C8—C12	1.503 (5)	C18—H18	0.9300
C9—C10	1.481 (5)	C19—H19	0.9300
C6—C1—C2	123.0 (4)	C12—C11—H11A	110.6
C6—C1—Br1	116.1 (3)	C10—C11—H11B	110.6
C2—C1—Br1	120.9 (3)	C12—C11—H11B	110.6
C3—C2—C1	115.3 (3)	H11A—C11—H11B	108.8
C3—C2—C7	123.3 (3)	C8—C12—C11	106.1 (3)
C1—C2—C7	121.4 (3)	C8—C12—H12A	110.5
C4—C3—C2	122.3 (4)	C11—C12—H12A	110.5
C4—C3—H3	118.9	C8—C12—H12B	110.5
C2—C3—H3	118.9	C11—C12—H12B	110.5
C5—C4—C3	119.9 (4)	H12A—C12—H12B	108.7
C5—C4—H4	120.1	C10—C13—C14	127.5 (3)
C3—C4—H4	120.1	C10—C13—H13	116.2
C6—C5—C4	120.3 (4)	C14—C13—H13	116.2
C6—C5—H5	119.8	C19—C14—C15	116.8 (3)
C4—C5—H5	119.8	C19—C14—C13	121.1 (3)
C5—C6—C1	119.3 (4)	C15—C14—C13	122.1 (3)
C5—C6—H6	120.4	C16—C15—C14	122.4 (4)
C1—C6—H6	120.4	C16—C15—Br2	118.0 (3)
C8—C7—C2	131.7 (3)	C14—C15—Br2	119.6 (3)
C8—C7—H7	114.2	C17—C16—C15	119.2 (4)
C2—C7—H7	114.2	C17—C16—H16	120.4
C7—C8—C9	118.8 (3)	C15—C16—H16	120.4
C7—C8—C12	132.2 (3)	C16—C17—C18	120.5 (4)
C9—C8—C12	108.9 (3)	C16—C17—H17	119.8
O1—C9—C10	125.4 (3)	C18—C17—H17	119.8
O1—C9—C8	126.7 (3)	C19—C18—C17	119.6 (4)
C10—C9—C8	107.9 (3)	C19—C18—H18	120.2
C13—C10—C9	121.0 (3)	C17—C18—H18	120.2
C13—C10—C11	129.9 (3)	C18—C19—C14	121.5 (4)
C9—C10—C11	108.8 (3)	C18—C19—H19	119.2
C10—C11—C12	105.5 (3)	C14—C19—H19	119.2
C10—C11—H11A	110.6
C6—C1—C2—C3	−0.1 (5)	C8—C9—C10—C11	11.3 (4)
Br1—C1—C2—C3	178.6 (3)	C13—C10—C11—C12	157.8 (4)
C6—C1—C2—C7	−179.1 (3)	C9—C10—C11—C12	−16.4 (4)
Br1—C1—C2—C7	−0.4 (5)	C7—C8—C12—C11	175.4 (4)
C1—C2—C3—C4	−0.1 (6)	C9—C8—C12—C11	−8.5 (4)
C7—C2—C3—C4	178.8 (4)	C10—C11—C12—C8	15.1 (4)
C2—C3—C4—C5	0.4 (6)	C9—C10—C13—C14	178.3 (3)
C3—C4—C5—C6	−0.5 (6)	C11—C10—C13—C14	4.8 (7)
C4—C5—C6—C1	0.2 (6)	C10—C13—C14—C19	39.3 (6)
C2—C1—C6—C5	0.1 (6)	C10—C13—C14—C15	−141.5 (4)
Br1—C1—C6—C5	−178.7 (3)	C19—C14—C15—C16	0.0 (5)
C3—C2—C7—C8	5.1 (6)	C13—C14—C15—C16	−179.2 (4)
C1—C2—C7—C8	−176.1 (4)	C19—C14—C15—Br2	−178.0 (3)
C2—C7—C8—C9	−176.3 (3)	C13—C14—C15—Br2	2.7 (5)
C2—C7—C8—C12	−0.6 (7)	C14—C15—C16—C17	0.7 (6)
C7—C8—C9—O1	−4.5 (6)	Br2—C15—C16—C17	178.8 (3)
C12—C8—C9—O1	178.8 (4)	C15—C16—C17—C18	−0.3 (7)
C7—C8—C9—C10	175.2 (3)	C16—C17—C18—C19	−0.9 (7)
C12—C8—C9—C10	−1.5 (4)	C17—C18—C19—C14	1.6 (6)
O1—C9—C10—C13	16.3 (6)	C15—C14—C19—C18	−1.2 (6)
C8—C9—C10—C13	−163.4 (3)	C13—C14—C19—C18	178.0 (4)
O1—C9—C10—C11	−168.9 (4)