Two substituted 2-pyrrolin-5-ones: chains built from a single N—H...O hydrogen bond

In each of methyl 2-methyl-5-oxo-2-pyrroline-3-carboxyl­ate, C₇H₉NO₃, and 3-acetyl-2-methyl-2-pyrrolin-5-one, C₇H₉NO₂, the pyrrolinone ring is planar. In each structure, mol­ecules are linked into simple chains by way of a single N—H...O hydrogen bond.

S1. Comment

As precursors for the synthesis of pyrrole derivatives, 2-pyrrolin-5-one derivatives have been prepared by the reaction of glyoxal with enaminoesters (San Feliciano et al., 1989). However, pyrrolinones accessible by this method are few in number. We report here the structures of two such compounds, namely 2-methyl-3-methoxycarbonyl-2-pyrrolin-5-one, (I) and 2-methyl-3-acetyl-2-pyrrolin-5-one, (II) (Figs. 1 and 2).

In each molecule, the five-membered ring (N1/C1–C4) is planar, with r.m.s deviations from the mean plane of 0.007 Å for (I) and 0.006 Å for (II). Within the pyrrolinone rings in (I) and (II), the bond distances provide evidence for π-conjugation and are different from those in substituted ethylenedi(2-pyrrolin-5-one) (Zhang et al., 2007). The N1—C2 and N1—C5 bonds [1.391 (2) and 1.359 (2) Å, respectively, for (I), and 1.396 (2) and 1.358 (2) Å, respectively, for (II)] are shorter than the corresponding bonds in ethylenedi(2-pyrrolin-5-one) [1.411 and 1.385 Å, respectively]. Conversely, the C2—C3 bond becomes longer [1.385 and 1.411 Å in (I) and (II), respectively, versus 1.349 Å in ethylenedi(2-pyrrolin-5-one)]. This indicates that the lone pair of electrons on atom N1 and the π electrons of C2═C3 in (I) and (II) exhibit significant delocalization compared with ethylenedi(2-pyrrolin-5-one).

In (I), the exocyclic bond angles show some significant variations. The two independent exocyclic angles (Table 1) at atom C2 differ by some 16°, while those at atom C3 differ by more than 10°. The sense of these deviations suggests strongly repulsive interactions between the methyl group on C2 and the methoxycarbonyl group, although there is a moderate intramolecular C—H···O hydrogen bond between them (Table 3). By contrast, the deviations of the angles (Table 4) at atoms C2 and C3 in (II) become larger, where there is no intramolecular interaction between methyl and acetyl groups. The sums of the three angles around atoms C2 and C3 in (I) are 360.00 (2) and 359.95 (2)°, respectively, and the corresponding values in (II) are 359.99 (2) and 359.92 (2)°, respectively.

It was found that the ¹H NMR spectrum of compound (II) shows the methylene H atoms of the pyrrolinone ring as a doublet at δ = 3.34 p.p.m., with an identical coupling constant (J = 2 Hz) to the C2—CH₃ H atoms. The feature is, however, inconsistent with that in (I), where the methylene H atoms give a quartet with coupling constant J = 2.4 Hz. This suggests that, even in solution, the methyl group bonded to C2 in (II) has a stable conformation with respect to the pyrrolinone ring.

In compound (I), the molecules are linked into zigzag chains by a single N—H···O hydrogen bond (Table 2). Heterocyclic atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor to carbonyl atom O1 in the molecule at (2 − x, y − 1/2, 5/2 − z), thus forming a C(4) chain (Bernstein et al., 1995) running along the (1, y, 5/4) direction and generated by a 2₁ screw axis along (1, y, 5/4) (Fig. 3). Four chains of this type pass through each unit cell; two of these chains, running along the directions (1, y, 1/4) and (0, y, 1/4), are related to one another by translational symmetry operations and are antiparallel to the other two chains, running along the (1, y, 3/4) and (0, y, −1/4) directions. There are no direction-specific interactions between adjacent chains.

In a similar way, the supramolecular structure of compound (II) takes on a simple chain packing. For the sake of simplicity, we shall omit any further consideration of the intermolecular C—H···O interactions involving a C—H bond from a methyl group, which are unlikely to have any structural significance. The molecules of (II) are connected into infinite chains by a single N—H···O hydrogen bond (Table 4). Heterocyclic atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor to carbonyl atom O1 in the molecule at (−x, y − 1/2, 3/2 − z), so generating a C(4) chain running along the (0, y, 3/4) direction and generated by a 2₁ screw axis along (0, y, 3/4) (Fig. 4). Four such chains pass through each unit cell; two of these chains, running along the directions (0, y, 3/4) and (1, y, 1/4), are related to one another by inversion and are hence antiparallel. There are no direction-specific interactions between adjacent chains.

S2. Experimental

Rather than the published method of San Feliciano et al. (1989), a modification of the synthetic procedure of [Please give reference for unmodified procedure] was used to prepare (I) and (II).

For compound, (I), methyl β-aminocrotonate (23 g) and excess glyoxal (40% in water, 25 ml) were mixed at room temperature in water (80 ml). The mixture was then allowed to stand overnight to give red crystals of (I) (yield 26%). The product was recrystallized from ethyl acetate. ¹H NMR (CDCl₃, δ, p.p.m.): 7.76 (s, 1H, NH), 3.71 (s, 3H, COOCH₃), 3.28 (q, J = 2.4 Hz, 2H, CH₂), 2.35 (t, J = 2.4 Hz, 3H, CH₃).

For the synthesis of (II), excess aqueous ammonia (17%, 0.22 mol) was introduced into a stirred solution of 2,4-pentanedione (20 g, 0.2 mol) in water (80 ml) at room temperature. After 2 h, excess glyoxal (40% in water, 25 ml) was added with stirring and the mixture was then allowed to stand overnight to give red crystals of (II) (yield 23%). The product was recrystallized from ethyl acetate. ¹H NMR (CDCl₃, δ, p.p.m.): 7.28 (s, 1H, NH), 3.34 (d, J = 2 Hz, 2H, CH₂), 2.38 (t, J = 2 Hz, 3H, CH₃), 2.20 (s, 3H, COCH₃).

S3. Refinement

H atoms were placed in idealized positions and allowed to ride on their respective parent atoms, with C—H = 0.98 Å and N—H = 0.86 Å, and with U_iso(H) = kU_eq(carrier atom), where k = 1.2 for C—H and N—H, and 1.5 for the methyl groups.

Computing details

For both compounds, data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); 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. The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The molecular structure of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 3. Part of the crystal structure of (I), showing the formation of a C(4) chain running along the (1, y, 5/4) direction. Atoms marked with an asterisk (*) and or an ampersand (&) are at the symmetry positions (2 − x, y − 1/2, 5/2 − z) and (2 − x, 1/2 + y, 5/2 − z), respectively.
	Fig. 4. Part of the crystal structure of (II), showing the formation of a C(4) chain running along the (0, y, 3/4) direction. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or an ampersand (&) are at the symmetry positions (−x, y − 1/2, 3/2 − z) and (−x, 1/2 + y, 3/2 − z), respectively.

(I) methyl 2-methyl-5-oxo-2-pyrroline-3-carboxylate

Crystal data

C7H9NO3	Z = 4
Mr = 155.15	F(000) = 328
Monoclinic, P21/c	Dx = 1.398 Mg m^−3
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 12.377 (3) Å	µ = 0.11 mm^−1
b = 7.562 (2) Å	T = 291 K
c = 7.880 (2) Å	Block, red
β = 91.509 (3)°	0.36 × 0.32 × 0.23 mm
V = 737.4 (3) Å^3

Data collection

Bruker SMART CCD area-detector diffractometer	1371 independent reflections
Radiation source: fine-focus sealed tube	1095 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ϕ and ω scans	θmax = 25.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −14→14
Tmin = 0.958, Tmax = 0.975	k = −9→9
5325 measured reflections	l = −9→9

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.142	H-atom parameters constrained
S = 1.31	w = 1/[σ^2(Fo^2) + (0.0731P)^2] where P = (Fo^2 + 2Fc^2)/3
1371 reflections	(Δ/σ)max < 0.001
102 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.24 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	1.02268 (11)	0.25843 (17)	1.23592 (18)	0.0546 (4)
O2	0.66840 (11)	0.49951 (17)	0.90559 (17)	0.0565 (5)
O3	0.60684 (10)	0.22581 (17)	0.85190 (16)	0.0476 (4)
N1	0.89483 (11)	0.07468 (18)	1.11840 (17)	0.0398 (4)
H1	0.9244	−0.0239	1.1481	0.048*
C2	0.79683 (14)	0.0866 (2)	1.0285 (2)	0.0357 (4)
C3	0.77377 (13)	0.2592 (2)	0.99831 (19)	0.0352 (5)
C4	0.86311 (14)	0.3709 (2)	1.0741 (2)	0.0381 (4)
H4A	0.8359	0.4515	1.1587	0.046*
H4B	0.8989	0.4385	0.9873	0.046*
C5	0.93881 (14)	0.2356 (2)	1.1542 (2)	0.0393 (5)
C6	0.68033 (14)	0.3413 (2)	0.9159 (2)	0.0380 (4)
C7	0.51227 (16)	0.3048 (3)	0.7723 (3)	0.0545 (6)
H7A	0.4730	0.3694	0.8556	0.082*
H7B	0.4669	0.2137	0.7243	0.082*
H7C	0.5339	0.3839	0.6842	0.082*
C1	0.73973 (16)	−0.0812 (2)	0.9848 (2)	0.0484 (5)
H1A	0.6764	−0.0556	0.9163	0.073*
H1B	0.7190	−0.1396	1.0871	0.073*
H1C	0.7870	−0.1568	0.9228	0.073*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0485 (9)	0.0394 (8)	0.0748 (9)	−0.0023 (6)	−0.0211 (7)	−0.0054 (6)
O2	0.0561 (9)	0.0278 (8)	0.0848 (10)	0.0039 (6)	−0.0157 (7)	0.0004 (6)
O3	0.0393 (8)	0.0343 (8)	0.0685 (9)	−0.0011 (5)	−0.0118 (6)	0.0007 (5)
N1	0.0410 (9)	0.0248 (8)	0.0531 (9)	0.0018 (6)	−0.0069 (7)	−0.0010 (5)
C2	0.0335 (9)	0.0317 (10)	0.0419 (9)	−0.0007 (6)	0.0004 (7)	−0.0013 (6)
C3	0.0359 (10)	0.0280 (9)	0.0416 (9)	−0.0016 (7)	0.0001 (7)	−0.0020 (6)
C4	0.0418 (10)	0.0282 (9)	0.0441 (9)	−0.0019 (7)	−0.0021 (8)	−0.0009 (6)
C5	0.0388 (10)	0.0315 (10)	0.0473 (9)	−0.0008 (7)	−0.0028 (8)	−0.0033 (7)
C6	0.0386 (10)	0.0304 (10)	0.0449 (9)	−0.0007 (7)	−0.0003 (7)	−0.0005 (6)
C7	0.0426 (11)	0.0469 (11)	0.0734 (13)	0.0027 (9)	−0.0143 (9)	0.0009 (9)
C1	0.0476 (12)	0.0302 (11)	0.0670 (12)	−0.0065 (8)	−0.0041 (9)	−0.0031 (8)

Geometric parameters (Å, º)

O1—C5	1.219 (2)	C3—C4	1.503 (2)
O2—C6	1.208 (2)	C4—C5	1.514 (2)
O3—C6	1.349 (2)	C4—H4A	0.9700
O3—C7	1.443 (2)	C4—H4B	0.9700
N1—C5	1.359 (2)	C7—H7A	0.9600
N1—C2	1.391 (2)	C7—H7B	0.9600
N1—H1	0.8600	C7—H7C	0.9600
C2—C3	1.356 (2)	C1—H1A	0.9600
C2—C1	1.489 (2)	C1—H1B	0.9600
C3—C6	1.451 (2)	C1—H1C	0.9600
C6—O3—C7	115.19 (14)	O1—C5—C4	129.27 (15)
C5—N1—C2	112.74 (14)	N1—C5—C4	106.16 (14)
C5—N1—H1	123.6	O2—C6—O3	122.40 (16)
C2—N1—H1	123.6	O2—C6—C3	123.26 (16)
C3—C2—N1	109.18 (15)	O3—C6—C3	114.34 (15)
C3—C2—C1	133.14 (17)	O3—C7—H7A	109.5
N1—C2—C1	117.68 (15)	O3—C7—H7B	109.5
C2—C3—C6	130.69 (16)	H7A—C7—H7B	109.5
C2—C3—C4	108.78 (15)	O3—C7—H7C	109.5
C6—C3—C4	120.47 (15)	H7A—C7—H7C	109.5
C3—C4—C5	103.09 (14)	H7B—C7—H7C	109.5
C3—C4—H4A	111.1	C2—C1—H1A	109.5
C5—C4—H4A	111.1	C2—C1—H1B	109.5
C3—C4—H4B	111.1	H1A—C1—H1B	109.5
C5—C4—H4B	111.1	C2—C1—H1C	109.5
H4A—C4—H4B	109.1	H1A—C1—H1C	109.5
O1—C5—N1	124.57 (16)	H1B—C1—H1C	109.5
C5—N1—C2—C3	1.4 (2)	C2—N1—C5—C4	−1.96 (19)
C5—N1—C2—C1	−178.83 (15)	C3—C4—C5—O1	−177.99 (18)
N1—C2—C3—C6	−177.45 (15)	C3—C4—C5—N1	1.74 (16)
C1—C2—C3—C6	2.8 (3)	C7—O3—C6—O2	−0.9 (2)
N1—C2—C3—C4	−0.10 (19)	C7—O3—C6—C3	178.84 (14)
C1—C2—C3—C4	−179.87 (18)	C2—C3—C6—O2	176.11 (17)
C2—C3—C4—C5	−1.00 (16)	C4—C3—C6—O2	−1.0 (2)
C6—C3—C4—C5	176.66 (14)	C2—C3—C6—O3	−3.6 (2)
C2—N1—C5—O1	177.78 (16)	C4—C3—C6—O3	179.34 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.86	1.99	2.832 (2)	168

Symmetry code: (i) −x+2, y−1/2, −z+5/2.

(II) 3-acetyl-2-methyl-2-pyrrolin-5-one

Crystal data

C7H9NO2	F(000) = 296
Mr = 139.15	Dx = 1.333 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2403 reflections
a = 12.1211 (18) Å	θ = 3.2–27.9°
b = 7.5078 (11) Å	µ = 0.10 mm^−1
c = 7.9542 (12) Å	T = 291 K
β = 106.740 (2)°	Block, red
V = 693.18 (18) Å^3	0.47 × 0.29 × 0.24 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1289 independent reflections
Radiation source: fine-focus sealed tube	1150 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.013
ϕ and ω scans	θmax = 25.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −14→14
Tmin = 0.954, Tmax = 0.977	k = −9→9
4420 measured reflections	l = −9→9

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.039	H-atom parameters constrained
wR(F^2) = 0.124	w = 1/[σ^2(Fo^2) + (0.0671P)^2 + 0.1884P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.002
1289 reflections	Δρmax = 0.23 e Å^−3
94 parameters	Δρmin = −0.17 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997a), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.028 (6)

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	−0.02438 (10)	0.26227 (16)	0.71716 (18)	0.0592 (4)
O2	0.35189 (12)	0.50023 (17)	0.5789 (2)	0.0665 (4)
N1	0.11219 (10)	0.07418 (16)	0.67140 (17)	0.0413 (4)
H1	0.0802	−0.0242	0.6873	0.050*
C2	0.21757 (12)	0.08393 (19)	0.63349 (18)	0.0367 (4)
C3	0.24331 (12)	0.25712 (18)	0.61258 (18)	0.0360 (4)
C4	0.14733 (13)	0.3716 (2)	0.63916 (19)	0.0396 (4)
H4A	0.1099	0.4384	0.5337	0.048*
H4B	0.1759	0.4541	0.7358	0.048*
C5	0.06589 (13)	0.2374 (2)	0.6804 (2)	0.0412 (4)
C1	0.27636 (16)	−0.0892 (2)	0.6268 (3)	0.0529 (5)
H1A	0.3499	−0.0675	0.6079	0.079*
H1B	0.2299	−0.1601	0.5323	0.079*
H1C	0.2871	−0.1513	0.7358	0.079*
C6	0.34462 (13)	0.3380 (2)	0.57991 (19)	0.0423 (4)
C7	0.44042 (14)	0.2258 (3)	0.5512 (2)	0.0519 (5)
H7A	0.4945	0.3008	0.5175	0.078*
H7B	0.4091	0.1405	0.4600	0.078*
H7C	0.4788	0.1643	0.6579	0.078*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0502 (7)	0.0478 (7)	0.0911 (10)	0.0036 (5)	0.0388 (7)	−0.0059 (6)
O2	0.0699 (9)	0.0400 (8)	0.1009 (11)	−0.0114 (6)	0.0427 (8)	0.0001 (6)
N1	0.0415 (7)	0.0302 (7)	0.0561 (8)	−0.0016 (5)	0.0203 (6)	−0.0013 (5)
C2	0.0359 (7)	0.0346 (8)	0.0399 (7)	0.0025 (6)	0.0112 (6)	−0.0013 (6)
C3	0.0361 (8)	0.0335 (8)	0.0389 (8)	0.0020 (6)	0.0117 (6)	−0.0003 (5)
C4	0.0451 (8)	0.0303 (7)	0.0455 (8)	0.0036 (6)	0.0164 (7)	0.0003 (6)
C5	0.0399 (8)	0.0366 (8)	0.0491 (8)	0.0030 (6)	0.0162 (6)	−0.0033 (6)
C1	0.0532 (10)	0.0368 (9)	0.0721 (11)	0.0095 (7)	0.0236 (8)	0.0013 (7)
C6	0.0433 (8)	0.0418 (9)	0.0426 (8)	−0.0033 (7)	0.0137 (6)	0.0002 (6)
C7	0.0403 (9)	0.0604 (11)	0.0589 (10)	−0.0007 (7)	0.0204 (7)	0.0018 (8)

Geometric parameters (Å, º)

O1—C5	1.2255 (18)	C4—H4A	0.9700
O2—C6	1.222 (2)	C4—H4B	0.9700
N1—C5	1.3583 (19)	C1—H1A	0.9600
N1—C2	1.3963 (19)	C1—H1B	0.9600
N1—H1	0.8600	C1—H1C	0.9600
C2—C3	1.359 (2)	C6—C7	1.504 (2)
C2—C1	1.490 (2)	C7—H7A	0.9600
C3—C6	1.459 (2)	C7—H7B	0.9600
C3—C4	1.5097 (19)	C7—H7C	0.9600
C3—C4	1.511 (2)
C5—N1—C2	112.43 (12)	N1—C5—C4	106.53 (12)
C5—N1—H1	123.8	C2—C1—H1A	109.5
C2—N1—H1	123.8	C2—C1—H1B	109.5
C3—C2—N1	109.47 (12)	H1A—C1—H1B	109.5
C3—C2—C1	134.51 (14)	C2—C1—H1C	109.5
N1—C2—C1	116.02 (13)	H1A—C1—H1C	109.5
C2—C3—C6	130.91 (14)	H1B—C1—H1C	109.5
C2—C3—C4	108.33 (12)	O2—C6—C3	118.83 (15)
C6—C3—C4	120.68 (13)	O2—C6—C7	119.82 (14)
C3—C4—C5	103.21 (12)	C3—C6—C7	121.35 (14)
C3—C4—H4A	111.1	C6—C7—H7A	109.5
C5—C4—H4A	111.1	C6—C7—H7B	109.5
C3—C4—H4B	111.1	H7A—C7—H7B	109.5
C5—C4—H4B	111.1	C6—C7—H7C	109.5
H4A—C4—H4B	109.1	H7A—C7—H7C	109.5
O1—C5—N1	124.12 (14)	H7B—C7—H7C	109.5
O1—C5—C4	129.35 (14)
C5—N1—C2—C3	−1.20 (18)	C2—N1—C5—O1	−177.71 (14)
C5—N1—C2—C1	178.13 (13)	C2—N1—C5—C4	1.70 (17)
N1—C2—C3—C6	176.86 (14)	C3—C4—C5—O1	177.87 (16)
C1—C2—C3—C6	−2.3 (3)	C3—C4—C5—N1	−1.49 (15)
N1—C2—C3—C4	0.13 (16)	C2—C3—C6—O2	−174.52 (17)
C1—C2—C3—C4	−179.03 (17)	C4—C3—C6—O2	1.9 (2)
C2—C3—C4—C5	0.82 (15)	C2—C3—C6—C7	4.3 (2)
C6—C3—C4—C5	−176.30 (13)	C4—C3—C6—C7	−179.34 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.86	1.98	2.819 (2)	166

Symmetry code: (i) −x, y−1/2, −z+3/2.