2-(2-Oxopyrrolidin-1-yl)­butyr­amide

The title compound, C₈H₁₄N₂O₂, also known as levetiracetam and (−)-(S)-α-ethyl-2-oxo-1-pyrrolidineacet­amide, was synthesized from L-me­thionine. The pyrrolidinone ring has a half-chair conformation. Screw-related mol­ecules are linked by N—H...O hydrogen bonds to form layers parallel to the bc plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.045
• wR factor = 0.144
• Data-to-parameter ratio = 8.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT241_ALERT_2_C Check High   U(eq) as Compared to Neighbors ....         C3
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          7

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           26.49
           From the CIF: _reflns_number_total                960
           Count of symmetry unique reflns          971
           Completeness (_total/calc)             98.87%
           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

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   1 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
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

---

Computing details

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

(-)-(S)-α-ethyl-2-oxo-1-pyrrolidineacetamide (2S)-2-(2-Oxo-pyrrolidin-1-yl)butanamide

Crystal data

C8H14N2O2	F(000) = 184
Mr = 170.21	Dx = 1.294 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 789 reflections
a = 6.272 (5) Å	θ = 3.4–23.1°
b = 7.993 (5) Å	µ = 0.09 mm^−1
c = 9.199 (7) Å	T = 293 K
β = 108.645 (9)°	Plate, colorless
V = 437.0 (6) Å^3	0.20 × 0.18 × 0.16 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	731 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.048
Graphite monochromator	θmax = 26.5°, θmin = 2.3°
ω scans	h = −7→7
2515 measured reflections	k = −9→9
960 independent reflections	l = −4→11

Refinement

Refinement on F^2	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0884P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.045	(Δ/σ)max = 0.001
wR(F^2) = 0.144	Δρmax = 0.23 e Å^−3
S = 1.08	Δρmin = −0.22 e Å^−3
960 reflections	Extinction correction: SHELXL97
110 parameters	Extinction coefficient: 0.24 (4)

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
O1	1.0302 (5)	0.6840 (4)	1.0293 (3)	0.0435 (8)
O2	0.9548 (5)	0.8292 (4)	0.4936 (4)	0.0495 (9)
N1	0.7650 (5)	0.8048 (4)	0.8259 (3)	0.0298 (8)
N2	0.9462 (6)	1.0263 (4)	0.6654 (4)	0.0398 (9)
H2A	0.9881	1.1034	0.6153	0.048*
H2B	0.9208	1.0502	0.7496	0.048*
C1	0.8577 (6)	0.7674 (4)	0.9763 (4)	0.0319 (9)
C2	0.7160 (7)	0.8422 (6)	1.0647 (5)	0.0428 (10)
H2C	0.6836	0.7601	1.1324	0.051*
H2D	0.7908	0.9375	1.1250	0.051*
C3	0.5051 (10)	0.8950 (9)	0.9417 (6)	0.0708 (18)
H3A	0.3837	0.8181	0.9378	0.085*
H3B	0.4610	1.0061	0.9636	0.085*
C4	0.5497 (7)	0.8948 (6)	0.7927 (5)	0.0446 (11)
H4A	0.4309	0.8373	0.7146	0.053*
H4B	0.5625	1.0081	0.7585	0.053*
C5	0.9209 (6)	0.8706 (5)	0.6132 (4)	0.0335 (9)
C6	0.8481 (6)	0.7369 (4)	0.7079 (4)	0.0289 (8)
H6	0.9840	0.6732	0.7616	0.035*
C7	0.6836 (7)	0.6122 (6)	0.6063 (4)	0.0394 (10)
H7A	0.5479	0.6708	0.5477	0.047*
H7B	0.7501	0.5635	0.5343	0.047*
C8	0.6220 (9)	0.4740 (6)	0.6972 (6)	0.0587 (13)
H8A	0.7551	0.4134	0.7531	0.088*
H8B	0.5173	0.3993	0.6285	0.088*
H8C	0.5543	0.5213	0.7678	0.088*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0480 (17)	0.0472 (16)	0.0323 (15)	0.0101 (14)	0.0085 (13)	0.0056 (13)
O2	0.074 (2)	0.0424 (17)	0.0452 (16)	−0.0083 (15)	0.0379 (17)	−0.0068 (14)
N1	0.0336 (16)	0.0329 (16)	0.0257 (15)	0.0025 (13)	0.0133 (14)	0.0020 (13)
N2	0.059 (2)	0.0312 (17)	0.0358 (18)	−0.0075 (16)	0.0244 (17)	−0.0008 (14)
C1	0.040 (2)	0.0277 (19)	0.0285 (19)	−0.0024 (17)	0.0119 (17)	0.0017 (16)
C2	0.055 (3)	0.043 (2)	0.038 (2)	−0.008 (2)	0.026 (2)	−0.0065 (19)
C3	0.076 (3)	0.089 (4)	0.061 (3)	0.045 (3)	0.041 (3)	0.022 (3)
C4	0.035 (2)	0.058 (3)	0.042 (2)	0.011 (2)	0.014 (2)	0.001 (2)
C5	0.036 (2)	0.035 (2)	0.031 (2)	0.0007 (16)	0.0121 (17)	0.0007 (16)
C6	0.0333 (19)	0.0303 (18)	0.0242 (18)	0.0020 (15)	0.0109 (16)	0.0014 (15)
C7	0.047 (2)	0.044 (2)	0.0289 (19)	−0.0084 (19)	0.0139 (19)	−0.0056 (18)
C8	0.073 (3)	0.053 (3)	0.048 (3)	−0.028 (2)	0.016 (3)	−0.004 (2)

Geometric parameters (Å, º)

O1—C1	1.231 (5)	C3—H3A	0.97
O2—C5	1.231 (5)	C3—H3B	0.97
N1—C1	1.352 (5)	C4—H4A	0.97
N1—C6	1.451 (4)	C4—H4B	0.97
N1—C4	1.473 (5)	C5—C6	1.538 (5)
N2—C5	1.325 (5)	C6—C7	1.521 (6)
N2—H2A	0.86	C6—H6	0.98
N2—H2B	0.86	C7—C8	1.508 (6)
C1—C2	1.507 (6)	C7—H7A	0.97
C2—C3	1.500 (7)	C7—H7B	0.97
C2—H2C	0.97	C8—H8A	0.96
C2—H2D	0.97	C8—H8B	0.96
C3—C4	1.484 (6)	C8—H8C	0.96
C1—N1—C6	122.9 (3)	N1—C4—H4B	111.0
C1—N1—C4	112.7 (3)	C3—C4—H4B	111.0
C6—N1—C4	123.5 (3)	H4A—C4—H4B	109.0
C5—N2—H2A	120.0	O2—C5—N2	122.8 (4)
C5—N2—H2B	120.0	O2—C5—C6	119.1 (3)
H2A—N2—H2B	120.0	N2—C5—C6	118.0 (3)
O1—C1—N1	124.1 (3)	N1—C6—C7	111.7 (3)
O1—C1—C2	126.6 (4)	N1—C6—C5	114.0 (3)
N1—C1—C2	109.3 (3)	C7—C6—C5	111.9 (3)
C3—C2—C1	103.5 (3)	N1—C6—H6	106.2
C3—C2—H2C	111.1	C7—C6—H6	106.2
C1—C2—H2C	111.1	C5—C6—H6	106.2
C3—C2—H2D	111.1	C8—C7—C6	112.5 (3)
C1—C2—H2D	111.1	C8—C7—H7A	109.1
H2C—C2—H2D	109.0	C6—C7—H7A	109.1
C4—C3—C2	108.4 (4)	C8—C7—H7B	109.1
C4—C3—H3A	110.0	C6—C7—H7B	109.1
C2—C3—H3A	110.0	H7A—C7—H7B	107.8
C4—C3—H3B	110.0	C7—C8—H8A	109.5
C2—C3—H3B	110.0	C7—C8—H8B	109.5
H3A—C3—H3B	108.4	H8A—C8—H8B	109.5
N1—C4—C3	103.9 (4)	C7—C8—H8C	109.5
N1—C4—H4A	111.0	H8A—C8—H8C	109.5
C3—C4—H4A	111.0	H8B—C8—H8C	109.5
C6—N1—C1—O1	6.0 (6)	C1—N1—C6—C7	110.1 (4)
C4—N1—C1—O1	175.5 (4)	C4—N1—C6—C7	−58.2 (5)
C6—N1—C1—C2	−173.6 (3)	C1—N1—C6—C5	−121.8 (4)
C4—N1—C1—C2	−4.1 (5)	C4—N1—C6—C5	69.8 (4)
O1—C1—C2—C3	−167.7 (4)	O2—C5—C6—N1	−166.9 (4)
N1—C1—C2—C3	11.8 (5)	N2—C5—C6—N1	13.7 (5)
C1—C2—C3—C4	−15.1 (6)	O2—C5—C6—C7	−39.0 (5)
C1—N1—C4—C3	−5.6 (5)	N2—C5—C6—C7	141.6 (4)
C6—N1—C4—C3	163.9 (4)	N1—C6—C7—C8	−54.5 (5)
C2—C3—C4—N1	13.0 (6)	C5—C6—C7—C8	176.4 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O2^i	0.86	2.15	2.995 (5)	168
N2—H2B···O1^ii	0.86	2.23	3.038 (5)	156
N2—H2B···N1	0.86	2.39	2.771 (5)	107
C6—H6···O1	0.98	2.39	2.840 (5)	107
C8—H8C···N1	0.96	2.59	2.919 (6)	100

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