Diethyl 1,1′-ethane-1,2-diylbis(2-methyl-5-oxo-4,5-dihydro-1H-pyrrole-3-car­­boxyl­ate)

In the title compound, C₁₈H₂₄N₂O₆, the two pyrrolinone rings are planar and adopt anti conformations. The mol­ecule lies on an inversion centre. The mol­ecules are linked into a three-dimensional framework structure by three independent C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.052
• wR factor = 0.139
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found





Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H8B    ..  O1      ..       2.71 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H7A    ..  O1      ..       2.71 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         78

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The reaction of ethylenediamine with ethyl acetoacetate yields dienamine,(I) (scheme 1), cyclization of which with glyoxal and thereafter rearrangement yields bicyclic pyrrolinone (II). We have reported the structure of the dienamine,(I) (Zhang et al., 2004). We have now prepared several novel ethylenedi(2-pyrrolin-5-one) derivatives (Zhang et al., 2007), but unfortunately, only the title compound, (II) has provided crystals suitable for single-crystal structure determination. We report here the molecular and supramolecular structure of the title compound, (II).

The structural unit in the title compound (Fig. 1) adopts a low-energy anti conformation with torsion angle N1—C4—C4ⁱ—N1ⁱ [symmetry code: (i) 1 - x,1 - y,1 - z] 180.0 (2)°. The anti-conformation is thought to result from a van der Waals repulsion effect between the two pyrrolinone rings. The pyrrolinone rings are perfectly planar, with a mean deviation of 0.006 Å. The dihedral angle between the planes of the two rings is 0 °, indicating that the two rings are parallel to one another. Within the pyrrolinone rings, there is a clear distinction between single and double bonds. The lengths for C2═C3 and C1═O1 bonds [1.349 (3) and 1.211 (3) Å, respectively] are shorter than the corresponding bonds found in the precursor (I) [1.370 (4) and 1.222 (4) Å, respectively; Zhang et al., 2004]. Conversely, the N1—C3 and C1—C2 bonds are longer [1.411 (3) and 1.459 (3) Å versus 1.342 (4) and 1.439 (4) Å, respectively]. It is also interestingly found that within pyrrolinone rings, the distance of 1.385 Å for N1—C9 is shorter than that of 1.411 Å for N1—C3 bond, indicating that as compared with C3═C2, the C9═O3 bond is in π-π conjugation with the N1 atom. The sum of the three angles around each of the N1, C3 and C2 atoms is 359.98 (2)°, implying that the N6, C3 and C2 atoms take on sp² hybridization.

In the molecule (II), there are two intramolecular C—H···O hydrogen bonds (Table 1), which, though not strong, contribute to the relatively stable co-planarity for the structural unit O2/C1/C2/C3/C7. This presumably sets the stage in turn for the interactions within the crystal lattice.

The molecules of compound (II) are linked by six independent C—H···O hydrogen bonds (Table 1) into a three-dimensional framework structure, whose formation is rather easily analysed in terms of two simple substructures, one of which is one-dimensional and the other is two-dimensional.

In the one-dimensional substructure, the methylene C8 atom in the pyrrolinone ring acts as a hydrogen-bond donor, via H8B, to the acyl atoms, thus forming the centrosymmetric R²₂(24) dimer (Bernstein et al., 1995) centred at (0,1/2,1/2); details of hydrogen-bonding geometry has been given in Table 1. Propagation by translation of these two hydrogen bonds generates a C(4) C(4) (Bernstein et al., 1995) hydrogen-bonded chains (column) along the a axis.

The column centred at (0,1/2,1/2) associates further via two independent bifurcated donor hydrogen bonds and two bifurcated acceptor hydrogen bonds with nearby four columns centred at (0,0,0), (0,1,0),(0,0,1) and (0,1,1), respectively. These lateral interactions reinforce structures by adding hydrogen bonds and extending them forming a two-dimensional substructure. The methyl atom C7 acts as a hydrogen-bond donor, via atoms H7A and H7C, to O atoms forming a two-dimensional hydrogen-bonded substructure (details in Table 1). The combination of the one- and two-dimensional substructures suffices to generate the three-dimensional framework structure (Fig. 2).

Related literature

For related literature, see: Bernstein et al. (1995); Zhang et al. (2004, 2007).

S2. Experimental

Into a three-necked round-bottomed flask equipped with a mechanical stirrer were introduced dienamine, (I), (28.4 g, 0.1 mol), ethanol (95%, 50 ml) and glyoxal (18 g, 40%). The mixture was then heated at about 333 K with stirring for 30 min under an inert atmosphere. Natural cooling of the reaction mixture overnight gave a crystalline product (yield: 18%). which was recrystallized from ethyl acetate. Single crystals of (II) were obtained by cooling of the hot solution of the above product in ethyl acetate very slowly over one week. ¹HNMR(CDCl₃, 400 MHz): δ 4.17 (q, J = 7.2 Hz, 4H, 2CH₂), δ 3.66 (s, 4H, 2CH₂), δ 3.23 (q, J = 2.4 Hz, 4H, 2CH₂), δ 2.40 (t, J = 2.4 Hz, 6H, 2CH₃), δ 1.27 (t, J = 7.2 Hz, 6H, 2CH₃).

S3. Refinement

H atoms were placed in idealized positions and were allowed to ride on the respective parent atoms with C—H = 0.98 Å and N—H = 0.86 Å, and with U_iso(H) = xU_eq(carrier atom), where x = 1.2 for C—H and N—H.

Computing details

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

Figures

	Fig. 1. A view of the molecule of (II); displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Part of the crystal structure of (II), showing the formation of two-dimensional substructure; H atoms not involved in the motifs have been omitted for clarity.
	Fig. 3. The formation of the title compound.

Diethyl 1,1'-ethane-1,2-diylbis(2-methyl-5-oxo-4,5-dihydro-1H-pyrrole-3-carboxylate)

Crystal data

C18H24N2O6	F(000) = 388
Mr = 364.39	Dx = 1.306 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1143 reflections
a = 4.5403 (10) Å	θ = 2.5–20.9°
b = 12.418 (3) Å	µ = 0.10 mm^−1
c = 16.439 (4) Å	T = 291 K
β = 91.812 (3)°	Block, colourless
V = 926.4 (4) Å^3	0.30 × 0.15 × 0.12 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	1716 independent reflections
Radiation source: fine-focus sealed tube	1164 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
φ and ω scans	θmax = 25.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1997a)	h = −5→5
Tmin = 0.971, Tmax = 0.988	k = −15→14
6085 measured reflections	l = −19→19

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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.139	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0615P)^2 + 0.2115P] where P = (Fo^2 + 2Fc^2)/3
1716 reflections	(Δ/σ)max < 0.001
120 parameters	Δρmax = 0.17 e Å^−3
78 restraints	Δρmin = −0.14 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
O1	1.1869 (4)	0.81344 (14)	0.73896 (11)	0.0720 (6)
O2	1.1711 (4)	0.64213 (13)	0.78091 (9)	0.0626 (5)
O3	0.3884 (4)	0.74182 (16)	0.49802 (11)	0.0807 (6)
N1	0.5743 (4)	0.60518 (15)	0.57889 (11)	0.0524 (5)
C1	1.0922 (5)	0.72278 (18)	0.73102 (13)	0.0509 (6)
C2	0.8829 (5)	0.69234 (17)	0.66586 (12)	0.0472 (5)
C3	0.7712 (4)	0.59462 (17)	0.64654 (12)	0.0451 (5)
C4	0.4149 (5)	0.5203 (2)	0.53604 (14)	0.0590 (6)
H4A	0.2245	0.5473	0.5169	0.071*
H4B	0.3813	0.4611	0.5731	0.071*
C5	1.3733 (6)	0.6677 (2)	0.84821 (14)	0.0687 (7)
H5A	1.2941	0.7254	0.8808	0.082*
H5B	1.5615	0.6908	0.8280	0.082*
C6	1.4108 (8)	0.5687 (3)	0.89787 (18)	0.1009 (11)
H6A	1.2285	0.5517	0.9230	0.151*
H6B	1.5615	0.5803	0.9392	0.151*
H6C	1.4668	0.5101	0.8636	0.151*
C7	0.8173 (6)	0.48586 (17)	0.68252 (15)	0.0613 (7)
H7A	0.9800	0.4881	0.7212	0.092*
H7B	0.8593	0.4354	0.6402	0.092*
H7C	0.6425	0.4639	0.7094	0.092*
C8	0.7540 (5)	0.77494 (18)	0.60915 (14)	0.0566 (6)
H8A	0.9063	0.8096	0.5784	0.068*
H8B	0.6477	0.8294	0.6387	0.068*
C9	0.5496 (5)	0.7116 (2)	0.55439 (14)	0.0575 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0810 (13)	0.0532 (10)	0.0810 (12)	−0.0135 (9)	−0.0110 (10)	−0.0072 (9)
O2	0.0747 (12)	0.0589 (10)	0.0531 (9)	−0.0057 (8)	−0.0155 (8)	−0.0015 (8)
O3	0.0725 (13)	0.1035 (15)	0.0649 (11)	0.0129 (10)	−0.0145 (10)	0.0175 (10)
N1	0.0479 (11)	0.0587 (12)	0.0502 (10)	−0.0034 (9)	−0.0018 (8)	−0.0048 (9)
C1	0.0487 (13)	0.0517 (14)	0.0526 (13)	0.0012 (11)	0.0036 (10)	−0.0060 (11)
C2	0.0488 (13)	0.0452 (12)	0.0476 (11)	−0.0003 (10)	0.0020 (10)	−0.0016 (10)
C3	0.0407 (12)	0.0518 (13)	0.0427 (11)	−0.0015 (10)	0.0026 (9)	−0.0025 (10)
C4	0.0465 (13)	0.0757 (17)	0.0549 (13)	−0.0113 (12)	0.0001 (10)	−0.0131 (12)
C5	0.0692 (17)	0.085 (2)	0.0506 (14)	−0.0030 (14)	−0.0114 (12)	−0.0105 (13)
C6	0.138 (3)	0.090 (2)	0.0721 (19)	0.016 (2)	−0.0422 (19)	−0.0024 (17)
C7	0.0724 (16)	0.0497 (14)	0.0615 (14)	−0.0048 (12)	−0.0037 (12)	0.0025 (11)
C8	0.0581 (15)	0.0505 (13)	0.0610 (14)	0.0040 (11)	0.0015 (12)	0.0022 (11)
C9	0.0514 (14)	0.0681 (16)	0.0532 (14)	0.0061 (12)	0.0037 (11)	0.0049 (12)

Geometric parameters (Å, º)

O1—C1	1.211 (3)	C4—H4B	0.9700
O2—C1	1.336 (3)	C5—C6	1.482 (4)
O2—C5	1.450 (3)	C5—H5A	0.9700
O3—C9	1.221 (3)	C5—H5B	0.9700
N1—C9	1.385 (3)	C6—H6A	0.9600
N1—C3	1.411 (3)	C6—H6B	0.9600
N1—C4	1.449 (3)	C6—H6C	0.9600
C1—C2	1.459 (3)	C7—H7A	0.9600
C2—C3	1.349 (3)	C7—H7B	0.9600
C2—C8	1.493 (3)	C7—H7C	0.9600
C3—C7	1.487 (3)	C8—C9	1.496 (3)
C4—C4^i	1.521 (4)	C8—H8A	0.9700
C4—H4A	0.9700	C8—H8B	0.9700
C1—O2—C5	117.06 (18)	C6—C5—H5B	110.3
C9—N1—C3	111.19 (18)	H5A—C5—H5B	108.5
C9—N1—C4	121.21 (19)	C5—C6—H6A	109.5
C3—N1—C4	127.58 (19)	C5—C6—H6B	109.5
O1—C1—O2	122.9 (2)	H6A—C6—H6B	109.5
O1—C1—C2	122.7 (2)	C5—C6—H6C	109.5
O2—C1—C2	114.35 (19)	H6A—C6—H6C	109.5
C3—C2—C1	129.6 (2)	H6B—C6—H6C	109.5
C3—C2—C8	109.52 (19)	C3—C7—H7A	109.5
C1—C2—C8	120.90 (19)	C3—C7—H7B	109.5
C2—C3—N1	109.02 (18)	H7A—C7—H7B	109.5
C2—C3—C7	132.5 (2)	C3—C7—H7C	109.5
N1—C3—C7	118.43 (18)	H7A—C7—H7C	109.5
N1—C4—C4^i	111.2 (2)	H7B—C7—H7C	109.5
N1—C4—H4A	109.4	C2—C8—C9	103.77 (19)
C4^i—C4—H4A	109.4	C2—C8—H8A	111.0
N1—C4—H4B	109.4	C9—C8—H8A	111.0
C4^i—C4—H4B	109.4	C2—C8—H8B	111.0
H4A—C4—H4B	108.0	C9—C8—H8B	111.0
O2—C5—C6	107.3 (2)	H8A—C8—H8B	109.0
O2—C5—H5A	110.3	O3—C9—N1	123.7 (2)
C6—C5—H5A	110.3	O3—C9—C8	129.8 (2)
O2—C5—H5B	110.3	N1—C9—C8	106.47 (19)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···O2	0.96	2.31	2.966 (4)	125
C8—H8B···O1^ii	0.97	2.71	3.429 (3)	131
C7—H7C···O1^iii	0.96	2.55	3.417 (3)	150
C7—H7A···O1^iv	0.96	2.71	3.337 (3)	123

Symmetry codes: (ii) x−1, y, z; (iii) −x+3/2, y−1/2, −z+3/2; (iv) −x+5/2, y−1/2, −z+3/2.