3,5-Dibromo-4-oxo-2,2,6,6-tetra­methyl­piperidin-1-yl oxide

Abstract

In the title compound, C₉H₁₄Br₂NO₂, the substituted ring exhibits a chair conformation. A crystallographic mirror plane, passing through the N atom, the O atoms and the C atom in the 4-position, bis­ects the mol­ecule.

Related literature

For medical applications of similar compounds, see: Aubert et al. (2011 ▶); Brike (1990 ▶); Xu et al. (2009 ▶). For puckering parameters see: Cremer & Pople(1975 ▶).

Experimental

Crystal data

• C₉H₁₄Br₂NO₂

• M _r = 328.03

• Orthorhombic,

• a = 11.6745 (9) Å

• b = 16.0848 (14) Å

• c = 5.9301 (4) Å

• V = 1113.57 (15) ų

• Z = 4

• Mo Kα radiation

• μ = 7.26 mm⁻¹

• T = 298 K

• 0.45 × 0.42 × 0.18 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.139, T _max = 0.355

• 5193 measured reflections

• 1018 independent reflections

• 774 reflections with I > 2σ(I)

• R _int = 0.118

Refinement

• R[F ² > 2σ(F ²)] = 0.034

• wR(F ²) = 0.089

• S = 1.04

• 1018 reflections

• 72 parameters

• H-atom parameters constrained

• Δρ_max = 0.52 e Å⁻³

• Δρ_min = −0.64 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

3,5-dibromo-4-oxo-2,2,6,6-tetramethylpiperidin-1-yl oxide is an important intermediate medicament. It is synthesized in a wide range of medical applications (Aubert et al. (2011); Brike (1990); Xu et al. (2009)). The complete molecule of the title compound, C₉H₁₄Br₂NO₂, is generated by crystallographic mirror symmetry, with two O, one C in the 3-position and one N atom lying on the mirror plane, Fig1. The substituted cyclohexyl ring adopts a chair conformation ( Q_T=0.562 (4)Å, θ =19.0 (4)°, φ =180.0 (12)° ), Cremer & Pople, (1975)

Experimental

The title compound was synthetized by reaction between 4-Oxo-2,2,6,6-tetramethylpiperidin-1-yl oxide (2 mmol) and bromine (2 mmol), dissolved in CH₂CH₂Cl₂ and mixed together for 2 h. Large block crystals were precipitated, filtered ,washed with ethanol and dried in air (yield 80%).

Refinement

All H atoms were positioned geometrically(C—H = 0.96–0.98 Å,) and were refined as riding, with U_iso(H) = 1.2U_eq(carrier) or 1.5U_eq(methyl C).

Figures

Fig. 1.

The molecular structure of (I) showing 30% probability displacement ellipsoids.

Crystal data

C9H14Br2NO2	Dx = 1.957 Mg m−3
Mr = 328.03	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 1704 reflections
a = 11.6745 (9) Å	θ = 3.5–26.6°
b = 16.0848 (14) Å	µ = 7.26 mm−1
c = 5.9301 (4) Å	T = 298 K
V = 1113.57 (15) Å3	Block, orange
Z = 4	0.45 × 0.42 × 0.18 mm
F(000) = 644

Data collection

Bruker SMART CCD area-detector diffractometer	1018 independent reflections
Radiation source: fine-focus sealed tube	774 reflections with I > 2σ(I)
graphite	Rint = 0.118
phi and ω scans	θmax = 25.0°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −13→12
Tmin = 0.139, Tmax = 0.355	k = −19→18
5193 measured reflections	l = −6→7

Refinement

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.089	H-atom parameters constrained
S = 1.04	w = 1/[σ2(Fo2) + (0.0364P)2] where P = (Fo2 + 2Fc2)/3
1018 reflections	(Δ/σ)max < 0.001
72 parameters	Δρmax = 0.52 e Å−3
0 restraints	Δρmin = −0.64 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	0.28737 (4)	0.42632 (3)	0.59566 (7)	0.0414 (2)
N1	0.4892 (4)	0.2500	0.2492 (7)	0.0268 (11)
O1	0.5770 (4)	0.2500	0.1217 (6)	0.0448 (11)
O2	0.2994 (3)	0.2500	0.7814 (7)	0.0384 (10)
C1	0.4591 (3)	0.3333 (2)	0.3498 (6)	0.0237 (9)
C2	0.3343 (3)	0.3265 (2)	0.4364 (6)	0.0263 (9)
H2	0.2844	0.3206	0.3045	0.032*
C3	0.3177 (4)	0.2500	0.5827 (10)	0.0277 (13)
C4	0.5446 (3)	0.3542 (3)	0.5367 (7)	0.0354 (10)
H4A	0.5310	0.3188	0.6643	0.053*
H4B	0.5354	0.4112	0.5808	0.053*
H4C	0.6212	0.3456	0.4824	0.053*
C5	0.4652 (4)	0.3975 (3)	0.1615 (8)	0.0418 (11)
H5A	0.5425	0.4012	0.1069	0.063*
H5B	0.4416	0.4507	0.2182	0.063*
H5C	0.4155	0.3811	0.0405	0.063*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0384 (3)	0.0281 (3)	0.0576 (4)	0.00706 (19)	0.00867 (18)	−0.0047 (2)
N1	0.024 (2)	0.033 (3)	0.023 (3)	0.000	0.0032 (17)	0.000
O1	0.039 (3)	0.050 (3)	0.046 (3)	0.000	0.0234 (19)	0.000
O2	0.048 (3)	0.034 (2)	0.033 (3)	0.000	0.0153 (19)	0.000
C1	0.025 (2)	0.022 (2)	0.024 (2)	−0.0017 (17)	0.0009 (14)	−0.0011 (16)
C2	0.023 (2)	0.024 (2)	0.033 (2)	0.0032 (17)	−0.0028 (14)	−0.0031 (17)
C3	0.011 (3)	0.026 (3)	0.046 (4)	0.000	−0.001 (2)	0.000
C4	0.024 (2)	0.034 (2)	0.047 (3)	−0.001 (2)	−0.0046 (17)	−0.007 (2)
C5	0.053 (3)	0.034 (2)	0.039 (3)	−0.001 (2)	0.006 (2)	0.007 (2)

Geometric parameters (Å, °)

Br1—C2	1.942 (4)	C2—H2	0.9800
N1—O1	1.274 (5)	C3—C2i	1.518 (5)
N1—C1i	1.509 (4)	C4—H4A	0.9600
N1—C1	1.509 (4)	C4—H4B	0.9600
O2—C3	1.198 (6)	C4—H4C	0.9600
C1—C5	1.523 (6)	C5—H5A	0.9600
C1—C4	1.529 (5)	C5—H5B	0.9600
C1—C2	1.548 (5)	C5—H5C	0.9600
C2—C3	1.518 (5)
O1—N1—C1i	115.0 (2)	O2—C3—C2i	125.8 (2)
O1—N1—C1	115.0 (2)	O2—C3—C2	125.8 (2)
C1i—N1—C1	125.3 (4)	C2i—C3—C2	108.3 (5)
N1—C1—C5	107.5 (3)	C1—C4—H4A	109.5
N1—C1—C4	109.2 (3)	C1—C4—H4B	109.5
C5—C1—C4	110.6 (3)	H4A—C4—H4B	109.5
N1—C1—C2	106.7 (3)	C1—C4—H4C	109.5
C5—C1—C2	109.6 (3)	H4A—C4—H4C	109.5
C4—C1—C2	112.9 (3)	H4B—C4—H4C	109.5
C3—C2—C1	111.5 (3)	C1—C5—H5A	109.5
C3—C2—Br1	110.9 (3)	C1—C5—H5B	109.5
C1—C2—Br1	111.6 (3)	H5A—C5—H5B	109.5
C3—C2—H2	107.5	C1—C5—H5C	109.5
C1—C2—H2	107.5	H5A—C5—H5C	109.5
Br1—C2—H2	107.5	H5B—C5—H5C	109.5
O1—N1—C1—C5	46.0 (5)	C4—C1—C2—C3	−69.8 (4)
C1i—N1—C1—C5	−159.6 (3)	N1—C1—C2—Br1	174.9 (2)
O1—N1—C1—C4	−74.1 (4)	C5—C1—C2—Br1	−69.0 (3)
C1i—N1—C1—C4	80.3 (5)	C4—C1—C2—Br1	54.8 (4)
O1—N1—C1—C2	163.5 (4)	C1—C2—C3—O2	111.8 (5)
C1i—N1—C1—C2	−42.1 (6)	Br1—C2—C3—O2	−13.2 (6)
N1—C1—C2—C3	50.2 (4)	C1—C2—C3—C2i	−65.4 (5)
C5—C1—C2—C3	166.4 (3)	Br1—C2—C3—C2i	169.5 (2)

Symmetry codes: (i) x, −y+1/2, z.