r-2,c-6-Bis(4-bromo­phen­yl)-t-3,t-5-dimethyl­tetra­hydro­pyran-4-one

In the title compound, C₁₉H₁₈Br₂O₂, the tetra­hydro­pyran ring has a chair conformation with an equatorial disposition of all the methyl and p-bromo­phenyl groups. The structure is stabilized by inter­molecular C—H...O, C—H...π and Br...Br inter­actions [Br...Br = 3.4756 (9) Å], forming a zigzag layer arrangement.

Key indicators

• Single-crystal X-ray study
• T = 297 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.044
• wR factor = 0.094
• Data-to-parameter ratio = 16.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.88
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  Br2     ..       3.48 Ang.
PLAT707_ALERT_1_C D...A   Calc    3.410(5), Rep    3.403(5), Dev..       1.40 Sigma
              C14  -O1      1.555   6.657

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.884
            Tmax scaled      0.427 Tmin scaled      0.388
PLAT793_ALERT_1_G Check the Absolute Configuration of C1     = ...          S
PLAT793_ALERT_1_G Check the Absolute Configuration of C2     = ...          R
PLAT793_ALERT_1_G Check the Absolute Configuration of C4     = ...          S
PLAT793_ALERT_1_G Check the Absolute Configuration of C5     = ...          R

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

   5 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
   1 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

Pyran-4-one derivatives are very important, naturally available and biologically active six-membered heterocyclic compounds (Noller, 1966). Japp and Maitland were the first to report the synthesis of several substituted tetrahydropyran derivatives (Japp & Maitland, 1904). While reviewing the literature, depending upon the number and nature of the substituents and the level of unsaturation, different conformations are reported for the six-membered heterocyclic ring, namely, sofa (Ray et al., 1998), planar (Kumar et al., 1999), chair (Belakhov et al., 2002; Krishnamoorthy et al., 2003; Jose Kavitha et al., 2003) or twist boat (Usman et al., 2002). Moreover, the synthesized compound contains two pairs of chiral carbons with identical groups on each. According to Eliel, there can be four racemic and two meso forms (Eliel, 1962).

In the title compound C₁₉H₁₈Br₂O₂, as shown in Fig. 1, the tetrahydropyran ring adopts a chair conformation. Both the methyl groups and p-Br phenyl rings occupy equatorial positions. Similar kinds of compounds with p-Cl or p-CH₃ substituents reported earlier exist in the chair conformation with equatorial orientations of all the phenyl and methyl groups. The absolute configuration of the chiral atoms C1, C2, C4 and C5 are S, R, S and R, respectively.

The crystal structure is stabilized by intermolecular C—H···O, C—H···π and Br···Br interactions. These contacts facilitate the formation of a zigzag network extendend over the ac plane. In the crystal structure the adjacent layers are linked through C—H···π interactions, viz. C4—H4···Cgⁱ with H4···Cgⁱ = 2.766 Å, C4···Cgⁱ = 3.687 Å and C4—H4···Cgⁱ = 156°, where Cgⁱ denotes the centroid of the C12–C17 aryl ring of the molecule (symmetry code: i = 2 - x, 1/2 + y, 3/2 - z).

The molecules are also held together by C—H···O interactions between C14 and O1ⁱⁱ of 3.403 (5) Å, C14—H14···O1ⁱⁱ = 136°, symmetry code: ii = 1/2 + x, y, 3/2 - z. A short contact is also seen between Br1···Br2ⁱⁱⁱ (3.4756 (9) Å, symmetry code: iii = 5/2 - x,-y,-1/2 + z).

Related literature

For related literature, see: Baliah & Mangalam (1978); Belakhov et al. (2002); Eliel (1962); Japp & Maitland (1904); Jose Kavitha et al. (2003); Krishnamoorthy et al. (2003); Kumar et al. (1999); Noller (1966); Ray et al. (1998); Usman et al. (2002).

S2. Experimental

The title compound was obtained by the condensation of pentan-3-one and p-bromo benzaldehyde in a 1:2 molar ratio in ethanol by adopting the literature procedure for similar types of compounds (Baliah & Mangalam, 1978). Diffraction quality crystals were obtained by recrystallization of the obtained compound in ethanol.

S3. Refinement

All the hydrogen atoms were fixed geometrically and allowed to ride on the parent carbon atoms, with aromatic C—H = 0.93 Å, aliphatic C—H = 0.98 Å and methyl C—H = 0.96 Å. The displacement parameters were set for phenyl and aliphatic H atoms at U_iso(H) = 1.2U_eq(C) and for methyl H atoms at 1.5U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. ORTEP of the molecule with atoms represented as 50% probability ellipsoids.

r-2,c-6-Bis(4-bromophenyl)-t-3,t-5-dimethyltetrahydropyran-4-one

Crystal data

C19H18Br2O2	F(000) = 1744
Mr = 438.15	Dx = 1.605 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 5214 reflections
a = 15.146 (3) Å	θ = 2.1–26.0°
b = 9.1460 (18) Å	µ = 4.48 mm^−1
c = 26.180 (5) Å	T = 297 K
V = 3626.6 (12) Å^3	Rectangular, colourless
Z = 8	0.22 × 0.20 × 0.19 mm

Data collection

Bruker Kappa-APEXII CCD area-detector diffractometer	3450 independent reflections
Radiation source: fine-focus sealed tube	2171 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
φ and ω scans	θmax = 26.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −17→17
Tmin = 0.439, Tmax = 0.483	k = −10→10
38553 measured reflections	l = −32→29

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.094	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0317P)^2 + 4.4775P] where P = (Fo^2 + 2Fc^2)/3
3450 reflections	(Δ/σ)max = 0.002
210 parameters	Δρmax = 0.62 e Å^−3
0 restraints	Δρmin = −0.41 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	1.23772 (3)	0.02246 (7)	0.981200 (17)	0.0872 (2)
Br2	1.08186 (3)	0.16048 (6)	0.532667 (17)	0.08003 (19)
C1	0.9071 (2)	0.1921 (4)	0.74443 (12)	0.0387 (8)
H1	0.8595	0.1200	0.7473	0.046*
C2	0.8682 (2)	0.3470 (4)	0.75042 (13)	0.0460 (9)
H2	0.9174	0.4165	0.7488	0.055*
C3	0.8285 (2)	0.3578 (4)	0.80309 (14)	0.0484 (9)
C4	0.8888 (2)	0.3119 (4)	0.84640 (13)	0.0459 (9)
H4	0.9356	0.3856	0.8489	0.055*
C5	0.9333 (2)	0.1659 (4)	0.83367 (12)	0.0402 (8)
H5	0.8891	0.0879	0.8357	0.048*
C6	1.0073 (2)	0.1311 (4)	0.86997 (12)	0.0407 (8)
C7	0.9971 (3)	0.0304 (4)	0.90867 (13)	0.0518 (10)
H7	0.9431	−0.0168	0.9125	0.062*
C8	1.0649 (3)	−0.0019 (4)	0.94173 (14)	0.0592 (11)
H8	1.0572	−0.0709	0.9675	0.071*
C9	1.1438 (3)	0.0689 (5)	0.93619 (13)	0.0532 (10)
C10	1.1559 (2)	0.1721 (4)	0.89904 (14)	0.0550 (10)
H10	1.2094	0.2212	0.8962	0.066*
C11	1.0871 (2)	0.2026 (4)	0.86575 (14)	0.0496 (9)
H11	1.0950	0.2722	0.8402	0.059*
C12	0.9531 (2)	0.1727 (4)	0.69389 (12)	0.0384 (8)
C13	1.0388 (2)	0.2201 (4)	0.68676 (14)	0.0463 (9)
H13	1.0703	0.2579	0.7143	0.056*
C14	1.0784 (2)	0.2121 (4)	0.63948 (15)	0.0512 (10)
H14	1.1362	0.2437	0.6350	0.061*
C15	1.0313 (3)	0.1570 (4)	0.59899 (14)	0.0502 (10)
C16	0.9471 (3)	0.1062 (4)	0.60490 (14)	0.0509 (10)
H16	0.9163	0.0677	0.5773	0.061*
C17	0.9086 (2)	0.1129 (4)	0.65277 (13)	0.0458 (9)
H17	0.8518	0.0766	0.6574	0.055*
C18	0.8418 (3)	0.3087 (5)	0.89754 (15)	0.0745 (13)
H18A	0.8107	0.3990	0.9025	0.112*
H18B	0.8843	0.2960	0.9244	0.112*
H18C	0.8006	0.2289	0.8981	0.112*
C19	0.8032 (3)	0.3881 (5)	0.70866 (16)	0.0738 (13)
H19A	0.7555	0.3189	0.7082	0.111*
H19B	0.8327	0.3873	0.6762	0.111*
H19C	0.7802	0.4841	0.7152	0.111*
O1	0.75334 (19)	0.3972 (4)	0.81016 (11)	0.0765 (9)
O2	0.97028 (14)	0.1662 (2)	0.78362 (8)	0.0409 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0670 (3)	0.1321 (5)	0.0623 (3)	0.0304 (3)	−0.0187 (2)	0.0014 (3)
Br2	0.0892 (4)	0.0904 (4)	0.0605 (3)	0.0113 (3)	0.0319 (2)	0.0005 (2)
C1	0.0311 (19)	0.043 (2)	0.0426 (19)	−0.0031 (16)	−0.0013 (15)	0.0015 (16)
C2	0.036 (2)	0.047 (2)	0.055 (2)	0.0024 (17)	0.0000 (17)	0.0033 (19)
C3	0.034 (2)	0.049 (2)	0.062 (2)	0.0027 (18)	0.0028 (17)	−0.0037 (18)
C4	0.039 (2)	0.050 (2)	0.050 (2)	0.0006 (18)	0.0024 (16)	−0.0097 (17)
C5	0.036 (2)	0.044 (2)	0.0406 (19)	−0.0080 (17)	0.0015 (15)	0.0008 (16)
C6	0.045 (2)	0.039 (2)	0.0380 (18)	−0.0010 (17)	−0.0004 (16)	−0.0036 (17)
C7	0.054 (2)	0.054 (2)	0.048 (2)	−0.013 (2)	−0.0010 (18)	0.0052 (19)
C8	0.069 (3)	0.066 (3)	0.043 (2)	0.004 (2)	−0.001 (2)	0.0091 (19)
C9	0.054 (3)	0.068 (3)	0.037 (2)	0.015 (2)	−0.0064 (18)	−0.008 (2)
C10	0.036 (2)	0.068 (3)	0.062 (2)	−0.001 (2)	−0.0012 (18)	−0.001 (2)
C11	0.043 (2)	0.055 (2)	0.050 (2)	−0.003 (2)	0.0003 (18)	0.0107 (18)
C12	0.0322 (19)	0.038 (2)	0.0447 (19)	0.0023 (16)	−0.0010 (15)	0.0031 (16)
C13	0.035 (2)	0.054 (2)	0.050 (2)	−0.0040 (18)	−0.0035 (17)	0.0031 (18)
C14	0.033 (2)	0.058 (2)	0.063 (3)	−0.0003 (19)	0.0070 (19)	0.007 (2)
C15	0.049 (2)	0.050 (2)	0.051 (2)	0.011 (2)	0.0112 (18)	0.0035 (19)
C16	0.054 (3)	0.053 (2)	0.046 (2)	0.003 (2)	−0.0053 (18)	−0.0061 (18)
C17	0.036 (2)	0.053 (2)	0.048 (2)	−0.0065 (18)	0.0000 (16)	−0.0035 (18)
C18	0.061 (3)	0.107 (4)	0.055 (2)	0.019 (3)	0.010 (2)	−0.011 (2)
C19	0.068 (3)	0.087 (3)	0.066 (3)	0.032 (3)	−0.006 (2)	0.008 (2)
O1	0.0427 (17)	0.108 (3)	0.0783 (19)	0.0243 (17)	0.0096 (15)	0.0015 (18)
O2	0.0334 (13)	0.0489 (15)	0.0403 (12)	0.0071 (11)	−0.0021 (10)	−0.0006 (11)

Geometric parameters (Å, º)

Br1—C9	1.895 (4)	C8—H8	0.9300
Br2—C15	1.898 (3)	C9—C10	1.368 (5)
C1—O2	1.422 (4)	C10—C11	1.386 (5)
C1—C12	1.505 (5)	C10—H10	0.9300
C1—C2	1.543 (5)	C11—H11	0.9300
C1—H1	0.9800	C12—C13	1.382 (5)
C2—C3	1.508 (5)	C12—C17	1.382 (5)
C2—C19	1.519 (5)	C13—C14	1.377 (5)
C2—H2	0.9800	C13—H13	0.9300
C3—O1	1.208 (4)	C14—C15	1.373 (5)
C3—C4	1.515 (5)	C14—H14	0.9300
C4—C18	1.516 (5)	C15—C16	1.366 (5)
C4—C5	1.533 (5)	C16—C17	1.384 (5)
C4—H4	0.9800	C16—H16	0.9300
C5—O2	1.425 (4)	C17—H17	0.9300
C5—C6	1.503 (5)	C18—H18A	0.9600
C5—H5	0.9800	C18—H18B	0.9600
C6—C7	1.378 (5)	C18—H18C	0.9600
C6—C11	1.379 (5)	C19—H19A	0.9600
C7—C8	1.375 (5)	C19—H19B	0.9600
C7—H7	0.9300	C19—H19C	0.9600
C8—C9	1.368 (6)
O2—C1—C12	107.7 (3)	C8—C9—Br1	118.9 (3)
O2—C1—C2	109.7 (3)	C9—C10—C11	119.1 (4)
C12—C1—C2	112.0 (3)	C9—C10—H10	120.5
O2—C1—H1	109.2	C11—C10—H10	120.5
C12—C1—H1	109.2	C6—C11—C10	120.8 (3)
C2—C1—H1	109.2	C6—C11—H11	119.6
C3—C2—C19	112.6 (3)	C10—C11—H11	119.6
C3—C2—C1	107.8 (3)	C13—C12—C17	118.5 (3)
C19—C2—C1	113.7 (3)	C13—C12—C1	121.1 (3)
C3—C2—H2	107.5	C17—C12—C1	120.4 (3)
C19—C2—H2	107.5	C14—C13—C12	120.9 (3)
C1—C2—H2	107.5	C14—C13—H13	119.5
O1—C3—C2	122.4 (3)	C12—C13—H13	119.5
O1—C3—C4	122.4 (3)	C15—C14—C13	119.2 (3)
C2—C3—C4	115.2 (3)	C15—C14—H14	120.4
C3—C4—C18	112.6 (3)	C13—C14—H14	120.4
C3—C4—C5	110.1 (3)	C16—C15—C14	121.5 (3)
C18—C4—C5	112.4 (3)	C16—C15—Br2	119.1 (3)
C3—C4—H4	107.1	C14—C15—Br2	119.4 (3)
C18—C4—H4	107.1	C15—C16—C17	118.7 (3)
C5—C4—H4	107.1	C15—C16—H16	120.6
O2—C5—C6	106.8 (3)	C17—C16—H16	120.6
O2—C5—C4	111.8 (3)	C12—C17—C16	121.2 (3)
C6—C5—C4	112.0 (3)	C12—C17—H17	119.4
O2—C5—H5	108.7	C16—C17—H17	119.4
C6—C5—H5	108.7	C4—C18—H18A	109.5
C4—C5—H5	108.7	C4—C18—H18B	109.5
C7—C6—C11	118.3 (3)	H18A—C18—H18B	109.5
C7—C6—C5	121.5 (3)	C4—C18—H18C	109.5
C11—C6—C5	120.2 (3)	H18A—C18—H18C	109.5
C8—C7—C6	121.5 (4)	H18B—C18—H18C	109.5
C8—C7—H7	119.3	C2—C19—H19A	109.5
C6—C7—H7	119.3	C2—C19—H19B	109.5
C9—C8—C7	119.0 (4)	H19A—C19—H19B	109.5
C9—C8—H8	120.5	C2—C19—H19C	109.5
C7—C8—H8	120.5	H19A—C19—H19C	109.5
C10—C9—C8	121.3 (3)	H19B—C19—H19C	109.5
C10—C9—Br1	119.8 (3)	C1—O2—C5	113.6 (2)
O2—C1—C2—C3	−57.3 (3)	C7—C8—C9—Br1	−179.2 (3)
C12—C1—C2—C3	−176.8 (3)	C8—C9—C10—C11	−1.5 (6)
O2—C1—C2—C19	177.1 (3)	Br1—C9—C10—C11	178.7 (3)
C12—C1—C2—C19	57.7 (4)	C7—C6—C11—C10	1.1 (5)
C19—C2—C3—O1	−0.9 (5)	C5—C6—C11—C10	179.8 (3)
C1—C2—C3—O1	−127.2 (4)	C9—C10—C11—C6	0.5 (6)
C19—C2—C3—C4	177.5 (3)	O2—C1—C12—C13	−38.4 (4)
C1—C2—C3—C4	51.3 (4)	C2—C1—C12—C13	82.2 (4)
O1—C3—C4—C18	5.0 (5)	O2—C1—C12—C17	144.6 (3)
C2—C3—C4—C18	−173.4 (3)	C2—C1—C12—C17	−94.8 (4)
O1—C3—C4—C5	131.3 (4)	C17—C12—C13—C14	1.9 (5)
C2—C3—C4—C5	−47.1 (4)	C1—C12—C13—C14	−175.1 (3)
C3—C4—C5—O2	48.3 (4)	C12—C13—C14—C15	0.4 (6)
C18—C4—C5—O2	174.7 (3)	C13—C14—C15—C16	−1.9 (6)
C3—C4—C5—C6	168.1 (3)	C13—C14—C15—Br2	174.9 (3)
C18—C4—C5—C6	−65.5 (4)	C14—C15—C16—C17	1.0 (6)
O2—C5—C6—C7	−134.4 (3)	Br2—C15—C16—C17	−175.8 (3)
C4—C5—C6—C7	103.0 (4)	C13—C12—C17—C16	−2.8 (5)
O2—C5—C6—C11	47.0 (4)	C1—C12—C17—C16	174.2 (3)
C4—C5—C6—C11	−75.7 (4)	C15—C16—C17—C12	1.4 (6)
C11—C6—C7—C8	−1.7 (6)	C12—C1—O2—C5	−173.8 (3)
C5—C6—C7—C8	179.7 (3)	C2—C1—O2—C5	64.2 (3)
C6—C7—C8—C9	0.7 (6)	C6—C5—O2—C1	177.7 (3)
C7—C8—C9—C10	1.0 (6)	C4—C5—O2—C1	−59.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···Cg^i	0.98	2.77	3.687	156
C14—H14···O1^ii	0.93	2.68	3.403 (5)	136

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