3-Aza­spiro­[5.5]undecane-2,4-dione

In the title compound, C₁₀H₁₅N₁O₂, the cyclo­hexane ring adopts a chair conformation and the piperidine ring adopts an envelope conformation. In the crystal structure, hydrogen-bonded dimers are formed via N—H...O inter­actions, and the mol­ecular packing is stabilized by van der Waals inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.038
• wR factor = 0.087
• Data-to-parameter ratio = 18.1

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S1. Comment

As an efficient intermediate in the preparation of gabapentin, the title compound, (I), plays an important role in the organic synthesis (Ferrari et al., 2004). Bond lengths and angles in (I) show normal values (Allen et al., 1987). The cyclohexane ring has the expected chair conformation, atoms C3 and C8 having deviations of 0.648 (2) and −0.654 (2) Å, respectively, from the least-squares plane through the other four atoms. The piperidine ring adopts an envelope conformation, with atom C3 deviating by 0.654 (2) Å from the mean plane through the other five atoms. In the crystal structure, centrosymmetric R₂²(8) dimers (Etter, 1990) are formed through hydrogen-bonding interactions [N···O = 2.889 (1) Å] between the NH and carbonyl groups (Fig. 2). The molecular packing is further stabilized by van der Waals interactions.

S2. Experimental

A mixture of acetic anhydride (66.5 g, 0.65 mol), ammonium acetate (66.5 g, 0.86 mol) and 1,1-cyclohexane diacetic acid (100 g, 0.53 mol) was heated to 433–443 K for 8 h, eliminating by distillation the acetic acid that has formed. Water (200 ml) and secondary butyl alcohol (100 g) were added when the mixture was cooled to 363–383 K. The solution was neutralized to pH 9 using 30% of aqueous ammonia and the precipitate was collected, washed with water and recrystallized from methanol (300 ml) to give 84.2 g (yield 93.1%) of dry 3-azaspiro[5.5]undecane-2,4-dione (Ferrari et al., 2004). This was recrystallized from the mixed solvent of ethanol and acetone (4:1 v/v), giving colorless crystals of (I) suitable for X-ray diffraction.

S3. Refinement

The H atoms of the amino group were located from difference Fourier maps and included in the refinement based on the as-found N—H bond lengths, but their isotropic displacement paramenters were refined and fixed in the final stage. All other H atoms were placed in calculated positions, with C—H = 0.97 Å, and included in the refinement in riding model, with U_iso(H) = 1.2U_eq(carrier atom).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: CrystalStructure.

Figures

	Fig. 1. The molecular configuration and atom-numbering scheme for (I). Displacement ellipsoids are drawn at the 40% probability level. H atoms are drawn as spheres of arbitrary radius.
	Fig. 2. Partial packing digram for (I), showing the hydrogen-bonded (dashed line) dimer [symmetry code: (i) 1 − x, 2 − y, −z].

3-Azaspiro[5.5]undecane-2,4-dione

Crystal data

C10H15NO2	F(000) = 392.00
Mr = 181.23	Dx = 1.273 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71075 Å
Hall symbol: -P 2ybc	Cell parameters from 7272 reflections
a = 11.402 (7) Å	θ = 3.1–27.5°
b = 6.231 (3) Å	µ = 0.09 mm^−1
c = 13.942 (5) Å	T = 296 K
β = 107.324 (18)°	Block, colorless
V = 945.6 (8) Å^3	0.32 × 0.28 × 0.16 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID diffractometer	1530 reflections with F^2 > 2σ(F^2)
Detector resolution: 10.00 pixels mm^-1	Rint = 0.042
ω scans	θmax = 27.5°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −14→14
Tmin = 0.968, Tmax = 0.986	k = −8→7
8782 measured reflections	l = −18→18
2152 independent reflections

Refinement

Refinement on F^2	w = 1/[0.0002Fo^2 + σ(Fo^2)]/(4Fo^2)
R[F^2 > 2σ(F^2)] = 0.039	(Δ/σ)max < 0.001
wR(F^2) = 0.087	Δρmax = 0.30 e Å^−3
S = 1.04	Δρmin = −0.25 e Å^−3
2152 reflections	Extinction correction: Larson (1970)
119 parameters	Extinction coefficient: 76 (18)
H-atom parameters constrained

Special details

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY

Refinement. Refinement using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.47845 (9)	0.97923 (13)	0.11873 (5)	0.0374 (2)
O2	0.33514 (10)	0.52046 (13)	−0.13779 (6)	0.0445 (2)
N3	0.40478 (10)	0.74579 (16)	−0.00749 (6)	0.0303 (2)
C1	0.42409 (12)	0.81117 (19)	0.09022 (8)	0.0274 (3)
C2	0.37696 (12)	0.66930 (19)	0.15674 (8)	0.0283 (3)
C3	0.26047 (12)	0.54603 (18)	0.10060 (8)	0.0267 (3)
C4	0.28801 (13)	0.42831 (19)	0.01324 (9)	0.0340 (3)
C5	0.34224 (12)	0.56370 (19)	−0.05126 (8)	0.0309 (3)
C6	0.15126 (12)	0.6996 (2)	0.06179 (9)	0.0325 (3)
C7	0.10608 (13)	0.7963 (2)	0.14477 (10)	0.0401 (3)
C8	0.07698 (13)	0.6234 (2)	0.21151 (10)	0.0412 (4)
C9	0.18587 (13)	0.4760 (2)	0.25314 (9)	0.0358 (3)
C10	0.22866 (12)	0.37762 (19)	0.16956 (9)	0.0330 (3)
H21	0.3588	0.7577	0.2078	0.034*
H22	0.4406	0.5666	0.1886	0.034*
H41	0.2116	0.3684	−0.0292	0.042*
H42	0.3452	0.3130	0.0410	0.041*
H62	0.0837	0.6210	0.0167	0.038*
H61	0.1761	0.8147	0.0252	0.038*
H72	0.0332	0.8819	0.1151	0.049*
H71	0.1705	0.8872	0.1862	0.049*
H81	0.0085	0.5388	0.1713	0.051*
H82	0.0545	0.6901	0.2664	0.051*
H101	0.3013	0.2915	0.1993	0.040*
H102	0.1635	0.2866	0.1293	0.040*
H301	0.4316	0.8235	−0.0455	0.037*
H91	0.1632	0.3625	0.2918	0.044*
H92	0.2527	0.5592	0.2965	0.044*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0432 (6)	0.0406 (5)	0.0289 (4)	−0.0172 (4)	0.0117 (3)	−0.0036 (3)
O2	0.0642 (7)	0.0424 (5)	0.0291 (4)	−0.0079 (5)	0.0173 (4)	−0.0060 (4)
N3	0.0343 (6)	0.0340 (5)	0.0240 (4)	−0.0074 (4)	0.0106 (4)	0.0026 (4)
C1	0.0231 (7)	0.0327 (6)	0.0251 (5)	−0.0014 (5)	0.0053 (4)	0.0028 (5)
C2	0.0267 (7)	0.0337 (6)	0.0239 (5)	−0.0026 (5)	0.0066 (4)	0.0033 (4)
C3	0.0278 (7)	0.0245 (5)	0.0281 (5)	−0.0033 (5)	0.0088 (4)	0.0034 (4)
C4	0.0389 (8)	0.0281 (6)	0.0363 (6)	−0.0052 (5)	0.0130 (5)	−0.0015 (5)
C5	0.0340 (8)	0.0298 (6)	0.0290 (5)	0.0011 (5)	0.0096 (5)	0.0001 (5)
C6	0.0280 (7)	0.0320 (6)	0.0352 (6)	−0.0036 (5)	0.0060 (5)	0.0077 (5)
C7	0.0364 (9)	0.0353 (6)	0.0513 (7)	0.0071 (6)	0.0172 (6)	0.0083 (6)
C8	0.0382 (9)	0.0425 (7)	0.0488 (7)	0.0004 (6)	0.0219 (6)	0.0043 (6)
C9	0.0385 (8)	0.0360 (6)	0.0363 (6)	−0.0058 (6)	0.0164 (5)	0.0077 (5)
C10	0.0340 (8)	0.0267 (5)	0.0397 (6)	−0.0026 (5)	0.0131 (5)	0.0068 (5)

Geometric parameters (Å, º)

O1—C1	1.2215 (14)	C2—H21	0.970
O2—C5	1.2151 (14)	C2—H22	0.970
N3—C1	1.3754 (14)	C4—H41	0.970
N3—C5	1.3817 (15)	C4—H42	0.970
C1—C2	1.4924 (18)	C6—H62	0.970
C2—C3	1.5322 (16)	C6—H61	0.970
C3—C4	1.5323 (18)	C7—H72	0.970
C3—C6	1.5356 (17)	C7—H71	0.970
C3—C10	1.5378 (18)	C8—H81	0.970
C4—C5	1.495 (2)	C8—H82	0.970
C6—C7	1.524 (2)	C9—H91	0.970
C7—C8	1.523 (2)	C9—H92	0.970
C8—C9	1.5142 (19)	C10—H101	0.970
C9—C10	1.520 (2)	C10—H102	0.970
N3—H301	0.840
C1—N3—C5	126.16 (10)	C5—C4—H41	107.9
O1—C1—N3	119.49 (11)	C5—C4—H42	108.0
O1—C1—C2	123.18 (10)	H41—C4—H42	109.5
N3—C1—C2	117.33 (10)	C3—C6—H62	108.5
C1—C2—C3	113.41 (8)	C3—C6—H61	108.2
C2—C3—C4	107.12 (11)	C7—C6—H62	108.0
C2—C3—C6	110.86 (9)	C7—C6—H61	109.0
C2—C3—C10	110.65 (8)	H62—C6—H61	109.5
C4—C3—C6	110.79 (9)	C6—C7—H72	109.5
C4—C3—C10	108.22 (9)	C6—C7—H71	108.4
C6—C3—C10	109.16 (11)	C8—C7—H72	109.5
C3—C4—C5	115.31 (9)	C8—C7—H71	108.3
O2—C5—N3	119.58 (12)	H72—C7—H71	109.5
O2—C5—C4	123.71 (11)	C7—C8—H81	108.4
N3—C5—C4	116.70 (9)	C7—C8—H82	109.6
C3—C6—C7	113.63 (9)	C9—C8—H81	108.6
C6—C7—C8	111.62 (11)	C9—C8—H82	109.6
C7—C8—C9	111.12 (13)	H81—C8—H82	109.5
C8—C9—C10	111.38 (10)	C8—C9—H91	109.4
C3—C10—C9	113.16 (10)	C8—C9—H92	108.5
C1—N3—H301	118.2	C10—C9—H91	109.4
C5—N3—H301	115.6	C10—C9—H92	108.7
C1—C2—H21	108.3	H91—C9—H92	109.5
C1—C2—H22	108.4	C3—C10—H101	108.3
C3—C2—H21	108.5	C3—C10—H102	108.7
C3—C2—H22	108.6	C9—C10—H101	108.9
H21—C2—H22	109.5	C9—C10—H102	108.3
C3—C4—H41	108.0	H101—C10—H102	109.5
C3—C4—H42	108.0
C1—N3—C5—O2	−177.59 (12)	C4—C3—C6—C7	171.10 (11)
C1—N3—C5—C4	1.58 (18)	C6—C3—C4—C5	70.78 (14)
C5—N3—C1—O1	−178.11 (12)	C4—C3—C10—C9	−173.70 (10)
C5—N3—C1—C2	2.17 (18)	C10—C3—C4—C5	−169.58 (10)
O1—C1—C2—C3	148.84 (12)	C6—C3—C10—C9	−53.05 (12)
N3—C1—C2—C3	−31.44 (16)	C10—C3—C6—C7	52.03 (13)
C1—C2—C3—C4	53.29 (12)	C3—C4—C5—O2	−156.43 (12)
C1—C2—C3—C6	−67.70 (14)	C3—C4—C5—N3	24.43 (16)
C1—C2—C3—C10	171.04 (10)	C3—C6—C7—C8	−53.84 (14)
C2—C3—C4—C5	−50.25 (13)	C6—C7—C8—C9	54.34 (13)
C2—C3—C6—C7	−70.11 (14)	C7—C8—C9—C10	−55.47 (14)
C2—C3—C10—C9	69.22 (14)	C8—C9—C10—C3	56.07 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H301···O1^i	0.84	2.06	2.8885 (14)	171

Symmetry code: (i) −x+1, −y+2, −z.