(3R,8aS)-3-Ethyl-perhydro-pyrrolo[1,2-a]pyrazine-1,4-dione.

In the title compound, C(9)H(14)N(2)O(2), the pyrrolidine and piperazine rings adopt envelope and boat conformations, respectively. The chiral centers were assigned on the basis of the known stereogenic center of an enanti-omerically pure starting material and the trans relationship between the H atoms attached to these centers. The crystal packing is stabilized by an inter-molecular hydrogen bond between the N-H group and a carbonyl O atom of the diketopiperazine group, forming zigzag C(5) chains along [010].

Related literature

For general background to the chemistry and biological properties of diketopiperazines, see: Herbert & Kelleher (1994 ▶); Ciajolo et al. (1995 ▶); Morley et al. (1981 ▶); Kazuharu et al. (1990 ▶); Funabashi et al. (1994 ▶); Moyroud et al. (1996 ▶); Caballero et al. (2003 ▶); Onishi et al. (2003 ▶); Alberch et al. (2004 ▶); von Nussbaum et al. (2003 ▶). For related structures, see: Hendea et al. (2006 ▶).

Experimental

Crystal data

C9H14N2O2

M = 182.22

Monoclinic,

a = 6.8657 (4) Å

b = 9.9258 (17) Å

c = 7.0040 (5) Å

β = 90.892 (6)°

V = 477.25 (9) Å3

Z = 2

Mo Kα radiation

μ = 0.09 mm−1

T = 293 K

0.46 × 0.40 × 0.33 mm

Data collection

Enraf–Nonius CAD-4 diffractometer

1290 measured reflections

1200 independent reflections

937 reflections with I > 2σ(I)

R int = 0.032

3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F 2 > 2σ(F 2)] = 0.044

wR(F 2) = 0.120

S = 1.09

1200 reflections

119 parameters

1 restraint

H-atom parameters constrained

Δρmax = 0.17 e Å−3

Δρmin = −0.15 e Å−3

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 1996 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810001856/bh2268sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810001856/bh2268Isup2.hkl

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

C9H14N2O2	F(000) = 196
Mr = 182.22	Dx = 1.268 Mg m−3
Monoclinic, P21	Melting point: 407 K
Hall symbol: P 2yb	Mo Kα radiation, λ = 0.71073 Å
a = 6.8657 (4) Å	Cell parameters from 25 reflections
b = 9.9258 (17) Å	θ = 3.6–15.6°
c = 7.0040 (5) Å	µ = 0.09 mm−1
β = 90.892 (6)°	T = 293 K
V = 477.25 (9) Å3	Prism, colorless
Z = 2	0.46 × 0.40 × 0.33 mm

Enraf–Nonius CAD-4 diffractometer	Rint = 0.032
Radiation source: fine-focus sealed tube	θmax = 27.9°, θmin = 3.0°
graphite	h = −9→9
ω–2θ scans	k = −13→0
1290 measured reflections	l = −9→0
1200 independent reflections	3 standard reflections every 200 reflections
937 reflections with I > 2σ(I)	intensity decay: 1%

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.120	H-atom parameters constrained
S = 1.09	w = 1/[σ2(Fo2) + (0.0525P)2 + 0.0801P] where P = (Fo2 + 2Fc2)/3
1200 reflections	(Δ/σ)max < 0.001
119 parameters	Δρmax = 0.17 e Å−3
1 restraint	Δρmin = −0.15 e Å−3
0 constraints

	x	y	z	Uiso*/Ueq
C1	0.6671 (5)	0.5429 (3)	0.1100 (4)	0.0446 (7)
C3	0.8672 (4)	0.3662 (3)	−0.0490 (4)	0.0446 (7)
H3	1.0083	0.3519	−0.0400	0.054*
C4	0.7726 (4)	0.2617 (3)	0.0781 (4)	0.0428 (7)
C6	0.5113 (5)	0.2151 (3)	0.3021 (5)	0.0481 (7)
H6A	0.5912	0.1966	0.4145	0.058*
H6B	0.4732	0.1304	0.2435	0.058*
C7	0.3339 (5)	0.2985 (4)	0.3527 (5)	0.0646 (10)
H7A	0.3015	0.2867	0.4860	0.077*
H7B	0.2223	0.2732	0.2741	0.077*
C8	0.3944 (5)	0.4437 (4)	0.3131 (5)	0.0603 (9)
H8A	0.2816	0.5001	0.2878	0.072*
H8B	0.4681	0.4810	0.4199	0.072*
C8A	0.5200 (4)	0.4315 (3)	0.1373 (4)	0.0415 (6)
H8AA	0.4353	0.4263	0.0237	0.050*
C9	0.8066 (5)	0.3439 (4)	−0.2576 (5)	0.0572 (9)
H9A	0.8351	0.2514	−0.2924	0.069*
H9B	0.6670	0.3568	−0.2705	0.069*
C10	0.9082 (6)	0.4374 (5)	−0.3946 (5)	0.0691 (11)
H10A	1.0466	0.4307	−0.3753	0.104*
H10B	0.8673	0.5284	−0.3720	0.104*
H10C	0.8751	0.4124	−0.5235	0.104*
N2	0.8290 (4)	0.5027 (2)	0.0198 (4)	0.0486 (7)
H2	0.9129	0.5629	−0.0171	0.058*
N5	0.6154 (3)	0.3007 (2)	0.1667 (3)	0.0396 (6)
O1	0.6391 (4)	0.6573 (2)	0.1630 (4)	0.0643 (7)
O4	0.8399 (4)	0.1481 (2)	0.0937 (4)	0.0655 (7)

	U11	U22	U33	U12	U13	U23
C1	0.0549 (17)	0.0338 (15)	0.0452 (15)	0.0027 (13)	−0.0003 (13)	0.0037 (13)
C3	0.0380 (15)	0.0432 (17)	0.0528 (16)	0.0016 (12)	0.0064 (13)	0.0008 (14)
C4	0.0405 (15)	0.0384 (15)	0.0494 (16)	0.0032 (13)	0.0012 (13)	−0.0032 (13)
C6	0.0556 (18)	0.0402 (16)	0.0486 (16)	−0.0063 (14)	0.0040 (14)	0.0026 (14)
C7	0.061 (2)	0.067 (2)	0.066 (2)	0.0009 (19)	0.0250 (16)	0.005 (2)
C8	0.065 (2)	0.050 (2)	0.067 (2)	0.0113 (17)	0.0253 (16)	0.0011 (17)
C8A	0.0415 (14)	0.0351 (14)	0.0480 (15)	0.0053 (13)	0.0043 (12)	0.0018 (12)
C9	0.066 (2)	0.055 (2)	0.0507 (17)	−0.0062 (16)	0.0063 (16)	−0.0058 (15)
C10	0.077 (2)	0.079 (3)	0.0526 (19)	−0.003 (2)	0.0156 (17)	−0.0057 (19)
N2	0.0534 (15)	0.0378 (14)	0.0549 (15)	−0.0127 (12)	0.0085 (12)	−0.0031 (11)
N5	0.0416 (13)	0.0317 (12)	0.0457 (13)	0.0024 (10)	0.0051 (10)	0.0018 (11)
O1	0.0847 (18)	0.0346 (12)	0.0737 (16)	0.0033 (12)	0.0073 (14)	−0.0050 (12)
O4	0.0627 (14)	0.0468 (14)	0.0875 (17)	0.0208 (12)	0.0180 (12)	0.0095 (13)

C1—O1	1.210 (4)	C7—H7A	0.9700
C1—N2	1.347 (4)	C7—H7B	0.9700
C1—C8A	1.512 (4)	C8—C8A	1.519 (4)
C3—N2	1.464 (4)	C8—H8A	0.9700
C3—C4	1.519 (4)	C8—H8B	0.9700
C3—C9	1.529 (4)	C8A—N5	1.468 (4)
C3—H3	0.9800	C8A—H8AA	0.9800
C4—O4	1.223 (4)	C9—C10	1.513 (5)
C4—N5	1.312 (4)	C9—H9A	0.9700
C6—N5	1.467 (4)	C9—H9B	0.9700
C6—C7	1.519 (5)	C10—H10A	0.9600
C6—H6A	0.9700	C10—H10B	0.9600
C6—H6B	0.9700	C10—H10C	0.9600
C7—C8	1.527 (6)	N2—H2	0.8717
O1—C1—N2	123.9 (3)	C8A—C8—H8B	111.1
O1—C1—C8A	122.5 (3)	C7—C8—H8B	111.1
N2—C1—C8A	113.6 (3)	H8A—C8—H8B	109.0
N2—C3—C4	111.0 (2)	N5—C8A—C1	111.6 (2)
N2—C3—C9	113.7 (3)	N5—C8A—C8	102.4 (2)
C4—C3—C9	110.4 (3)	C1—C8A—C8	115.7 (3)
N2—C3—H3	107.1	N5—C8A—H8AA	109.0
C4—C3—H3	107.1	C1—C8A—H8AA	109.0
C9—C3—H3	107.1	C8—C8A—H8AA	109.0
O4—C4—N5	122.8 (3)	C10—C9—C3	113.3 (3)
O4—C4—C3	121.2 (3)	C10—C9—H9A	108.9
N5—C4—C3	116.0 (3)	C3—C9—H9A	108.9
N5—C6—C7	103.6 (3)	C10—C9—H9B	108.9
N5—C6—H6A	111.0	C3—C9—H9B	108.9
C7—C6—H6A	111.0	H9A—C9—H9B	107.7
N5—C6—H6B	111.0	C9—C10—H10A	109.5
C7—C6—H6B	111.0	C9—C10—H10B	109.5
H6A—C6—H6B	109.0	H10A—C10—H10B	109.5
C6—C7—C8	104.5 (3)	C9—C10—H10C	109.5
C6—C7—H7A	110.8	H10A—C10—H10C	109.5
C8—C7—H7A	110.8	H10B—C10—H10C	109.5
C6—C7—H7B	110.8	C1—N2—C3	125.6 (3)
C8—C7—H7B	110.8	C1—N2—H2	119.3
H7A—C7—H7B	108.9	C3—N2—H2	114.5
C8A—C8—C7	103.4 (3)	C4—N5—C6	123.2 (3)
C8A—C8—H8A	111.1	C4—N5—C8A	124.3 (2)
C7—C8—H8A	111.1	C6—N5—C8A	112.5 (2)
N2—C3—C4—O4	−152.4 (3)	O1—C1—N2—C3	−179.1 (3)
C9—C3—C4—O4	80.6 (4)	C8A—C1—N2—C3	0.2 (4)
N2—C3—C4—N5	28.2 (4)	C4—C3—N2—C1	−31.8 (4)
C9—C3—C4—N5	−98.8 (3)	C9—C3—N2—C1	93.3 (3)
N5—C6—C7—C8	−23.9 (4)	O4—C4—N5—C6	3.8 (5)
C6—C7—C8—C8A	36.4 (4)	C3—C4—N5—C6	−176.8 (3)
O1—C1—C8A—N5	−147.5 (3)	O4—C4—N5—C8A	−173.9 (3)
N2—C1—C8A—N5	33.2 (3)	C3—C4—N5—C8A	5.4 (4)
O1—C1—C8A—C8	−31.1 (4)	C7—C6—N5—C4	−175.5 (3)
N2—C1—C8A—C8	149.7 (3)	C7—C6—N5—C8A	2.5 (3)
C7—C8—C8A—N5	−33.9 (3)	C1—C8A—N5—C4	−37.8 (4)
C7—C8—C8A—C1	−155.4 (3)	C8—C8A—N5—C4	−162.1 (3)
N2—C3—C9—C10	59.2 (4)	C1—C8A—N5—C6	144.3 (3)
C4—C3—C9—C10	−175.3 (3)	C8—C8A—N5—C6	20.0 (3)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O4i	0.87	1.98	2.817 (3)	161

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O4i	0.87	1.98	2.817 (3)	161

Symmetry code: (i) .