The dipolar cyclo­addition of methyl acrylate to 5,6-diethyl-1-methyl-3-oxidopyrazinium

Helliwell, M.; You, Y.; Joule, J.A.

doi:10.1107/S1600536806017107

organic compounds

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ISSN: 2056-9890

Volume 62| Part 6| June 2006| Pages o2318-o2320

https://doi.org/10.1107/S1600536806017107

The dipolar cycloaddition of methyl acrylate to 5,6-diethyl-1-methyl-3-oxidopyrazinium

Madeleine Helliwell,^a Yun You ^a and John A. Joule ^a ^*

^aThe School of Chemistry, The University of Manchester, Manchester M13 9PL, England
^*Correspondence e-mail: john.joule@manchester.ac.uk

(Received 26 April 2006; accepted 9 May 2006; online 12 May 2006)

5,6-Diethylpyrazin-2-one reacts with iodomethane to give a quaternary salt, deprotonation of which, in situ, liberates a 3-oxidopyrazinium which undergoes a 1,3-dipolar cycloaddition with methyl acrylate to form methyl (Z)-5-ethyl-4-ethylidene-8-methyl-2-oxo-3,8-diazabicyclo[3.2.1]octane-6-endo-6-carboxylate. The crystal structure revealed (i) the existence of the imine product as its enamine tautomer, (ii) the Z geometry of the exocyclic double bond, and (iii) the endo orientation of the ester group. Pairwise hydrogen bonding between the NH H atom and the amide carbonyl group links the molecules into centrosymmetric dimers.

Comment

In our investigations of the 1,3-dipolar cycloaddition chemistry of 3-oxidopyraziniums (Kiss et al., 1987 ; Allway et al., 1990 ; Yates et al., 1995 ; Helliwell et al., 2006 ), we have demonstrated that these reactions efficiently produce bridged bicyclic systems – 3,8-diazabicyclo[3.2.1]octanes – which comprise key structural components of such biologically active natural products as anticancer quinocarcin (Takahashi & Tomita, 1983 ; Tomita et al., 1983 ; Hirayama & Shirahata, 1983 ) and antibiotic lemonomycin (He et al., 2000 ).

In a series of benchmark papers by Katritzky and co-workers (for reviews, see Dennis et al., 1976 ; Katritzky & Dennis, 1989 ) on the cycloadditions of 3-oxidopyridiniums, there were no examples of adduct formation using dipoles in which either one or two substituents were located on the 1,3-dipole at the future ring-junction positions. We have shown that one methyl group, so located, is not deleterious to the cycloaddition process using 1,5,6-trimethyl-3-oxidopyrazinium (Helliwell et al., 2006). This report describes our investigation of the reactivity of 5,6-diethyl-1-methyl-3-oxidopyrazinium, (3), in which a larger ethyl group is located at one of the future ring-junction positions and, in addition, this group is adjacent to another relatively bulky ethyl group.

5,6-Diethylpyrazin-2-one, (1), was prepared by the condensation of hexane-3,4-dione with glycinamide following the established method (Jones, 1949 ; Karmas & Spoerri, 1952 ; Yates et al., 1995). Reaction of (1) with iodomethane produced the methiodide (2), treatment of which with triethylamine allowed the generation of the zwitterion (3), in situ, and in the presence of methyl acrylate. As in all previous cases, the immediate products of such cycloadditions [(4) in this case] are not isolated but tautomerize to the more stable enamide structures, (5) in this case. Thus, the presence of even an ethyl group at a future ring-junction position does not prevent cycloaddition. It is noteworthy that, with increasing bulk, a greater proportion of endo isomer is formed, actually the only stereoisomer isolated in this case. The Z stereochemistry of the exocyclic double bond was established by the crystal structure study. Suitable crystals of the adduct were examined crystallographically, confirming the structure and stereochemistry (Fig. 1). Intermolecular hydrogen bonding between the NH H atom and the amide carbonyl group leads to the formation of centrosymmetric dimers (Table 1).

Figure 1
The molecular structure of (5), with displacement ellipsoids drawn at the 50% probability level.

Experimental

To hexane-3,4-dione (4.80 g, 0.04 mol) in water (5 ml) was added sodium metabisulfite (7.60 g, 0.04 mol) and the mixture stirred for 1 h at room temperature. An addition compound was precipitated as a gummy solid on addition of methanol (18 ml) and ethanol (6 ml) and separated by filtration. The solid was dissolved in water (5 ml) and glycinamide hydrochloride (2.27 g, 0.02 mol) was added. The pH was then adjusted to 8 with 10 M KOH and the mixture maintained at 333–353 K for 2 h. The pH was adjusted to 10 and the mixture kept at 323–333 K for 30 min. The mixture was cooled and adjusted to pH 6 with concentrated HCl, then cooled to 273 K. 5,6-Diethylpyrazin-3-one was precipitated as square white crystals (1.34 g, 44%; m.p. 443–445 K), δ_H (300 MHz, CDCl₃) 1.26 (3H, t, J = 7.5 Hz, CH₂CH₃), 1.34 (3H, t, J = 7.5 Hz, CH₂CH₃), 2.63 (2H, q, J = 7.5 Hz, CH₂CH₃), 2.66 (2H, q, J = 7.5 Hz, CH₂CH₃), 8.07 (1H, s, H-2), 13.32 (1H, s, NH); analysis found: C 62.64, H 7.95, N 16.25%; C₈H₁₂N₂O requires C, 63.13; H, 7.95; N, 18.41%.

5,6-Diethylpyrazin-2-one (500 mg, 3.3 mmol) and iodomethane (1.2 ml, 16.5 mmol) were heated under reflux in acetonitrile (25 ml) under N₂ for 24 h. The solvent was removed under vacuum. The residue was extracted with CH₂Cl₂ and the solid was filtered off to give the methiodide as a greenish crystalline solid (548 mg, 57%) which was used in the next step without further purification: Analysis: δ_H (300 MHz, D₂O) 1.20 (3H, t, J = 7.6 Hz, CH₂CH₃), 1.25 (3H, t, J = 7.6 Hz, CH₂CH₃), 2.80 (2H, q, J = 7.6 Hz, CH₂CH₃), 2.90 (2H, q, J = 7.6 Hz, CH₂CH₃), 4.20 (3H, s, NCH₃), 8.15 (1H, s, H-2).

A solution of 1-methyl-5,6-diethylpyrazin-3-onium iodide (100 mg, 0.725 mmol) with triethylamine (0.22 ml, 1.45 mmol) and methyl acrylate (0.33 ml, 3.63 mmol) in dry acetonitrile (5 ml) was heated at reflux for 1.5 h to give an orange solution. The solvent and excess methyl acrylate were evaporated under vacuum. From the residue a pure sample of methyl 5-ethyl-8-methyl-(Z)-4-ethylidene-2-oxo-3,8-diazabicyclo[3.2.1]octane-6-endo-6-carboxylate was obtained by flash chromatography (silica, n-hexane–EtOAc 7:3) as colourless plates (15 mg, 9%). Analysis: δ_H (300 MHz, CDCl₃) 1.01 (3H, t, J = 7 Hz, CH₂CH₃), 1.56 (3H, d, J = 7 Hz, CHCH₃), 1.02 1.66 (1H, m, one of CH₂CH₃), 2.13 1.03 (1H, m, one of CH₂CH₃), 2.25 (3H, s, NCH₃), 1.04 2.33 (1H, m, H-7), 2.48 (1H, dd, J = 5, 13 Hz, H-7), 1.05 3.21 (1H, dd, J = 5, 11 Hz, H-6), 3.58 (1H, d, J = 8 Hz, H-1), 1.06 3.64 (3H, s, OCH₃), 4.53 (1H, q, J = 7 Hz, CHCH₃), 1.07 6.95 (1H, s, NH).

Crystal data

C₁₃H₂₀N₂O₃
M_r = 252.31
Monoclinic, P 2₁ /c
a = 10.00 (2) Å
b = 8.842 (10) Å
c = 14.693 (10) Å
β = 90.36 (8)°
V = 1300 (3) Å³
Z = 4
D_x = 1.290 Mg m⁻³
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 (2) K
Plate, colourless
0.4 × 0.3 × 0.2 mm

Data collection

Rigaku R-AXIS diffractometer
φ scans
Absorption correction: none
10171 measured reflections
2173 independent reflections
1840 reflections with I > 2σ(I)
R_int = 0.042
θ_max = 25.0°

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.126
S = 1.06
2173 reflections
171 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F_o²) + (0.078P)² + 0.2408P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O3ⁱ	0.89 (2)	2.10 (2)	2.975 (3)	170.9 (16)
Symmetry code: (i) -x+1, -y, -z+1.

H atoms bonded to carbon were included in calculated positions using the riding model, with C—H distances of 0.93–0.98 Å and with U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for the other H atoms; H1 was found by difference Fourier methods and refined isotropically.

Data collection: MSC RAXIS11 Control Software (Molecular Structure Corporation, 1992 ); cell refinement: DENZO (Otwinowski & Minor, 1988 ); data reduction: DENZO; program(s) used to solve structure: SHELXS86 (Sheldrick, 1985 ) and TEXSAN (Molecular Structure Corporation, 1995 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL (Bruker, 2001 ).

Supporting information

Crystal structure: contains datablocks global, 5. DOI: https://doi.org/10.1107/S1600536806017107/kj2003sup1.cif

Structure factors: contains datablock 5. DOI: https://doi.org/10.1107/S1600536806017107/kj20035sup2.hkl

Computing details top

Data collection: MSC RAXIS11 Control Software (Molecular Structure Corporation, 1992); cell refinement: DENZO (Otwinowski, 1988); data reduction: DENZO; program(s) used to solve structure: SHELXS86 (Sheldrick, 1985) and TEXSAN (Molecular Structure Corporation, 1995); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL (Bruker, 2001).

methyl (Z)-5-ethyl-4-ethylidene-8-methyl-2-oxo-3,8-diazabicyclo[3.2.1]octane-6-endo- 6-carboxylate top

Crystal data top

C₁₃H₂₀N₂O₃	F(000) = 544
M_r = 252.31	D_x = 1.290 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 10171 reflections
a = 10.00 (2) Å	θ = 2.0–25.0°
b = 8.842 (10) Å	µ = 0.09 mm⁻¹
c = 14.693 (10) Å	T = 293 K
β = 90.36 (8)°	Plate, colourless
V = 1300 (3) Å³	0.4 × 0.3 × 0.2 mm
Z = 4

Data collection top

Rigaku R-AXIS diffractometer	1840 reflections with I > 2σ(I)
Radiation source: Rigaku rotating anode	R_int = 0.042
Graphite monochromator	θ_max = 25.0°, θ_min = 2.0°
40 x 5° φ scans	h = 0→11
10171 measured reflections	k = 0→10
2173 independent reflections	l = −17→17

Refinement top

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.126	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.078P)² + 0.2408P] where P = (F_o² + 2F_c²)/3
2173 reflections	(Δ/σ)_max < 0.001
171 parameters	Δρ_max = 0.18 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Special details top

Experimental. δ_C (75 MHz, CDCl₃) 158.5, 144.5, 138.3, 135.84, 25.0, 23.4, 13.9, 13.7; m/z (CI) 153 (MH⁺, 100%), 154 (15), 109 (12), 82 (12)

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two least-squares 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 least-squares planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	1.00713 (12)	0.37042 (15)	0.64648 (8)	0.0435 (4)
O2	0.91004 (14)	0.32829 (17)	0.51163 (8)	0.0529 (4)
O3	0.43880 (12)	0.18148 (13)	0.51024 (8)	0.0426 (4)
N1	0.62102 (13)	0.10340 (15)	0.58974 (9)	0.0292 (3)
H1	0.6108 (18)	0.014 (2)	0.5634 (12)	0.042 (5)*
N2	0.58051 (13)	0.33475 (14)	0.71113 (8)	0.0284 (3)
C1	0.72468 (15)	0.12658 (17)	0.65483 (10)	0.0254 (4)
C2	0.71966 (15)	0.28016 (17)	0.70353 (9)	0.0259 (4)
C3	0.77540 (15)	0.40708 (17)	0.63903 (10)	0.0292 (4)
H3	0.7945	0.4965	0.6763	0.035*
C4	0.65738 (16)	0.44507 (18)	0.57582 (11)	0.0341 (4)
H4A	0.6752	0.4129	0.5140	0.041*
H4B	0.6391	0.5528	0.5759	0.041*
C5	0.53965 (16)	0.35593 (17)	0.61632 (11)	0.0295 (4)
H5	0.4563	0.4139	0.6121	0.035*
C6	0.52718 (15)	0.20660 (18)	0.56728 (10)	0.0291 (4)
C7	0.81900 (16)	0.02317 (18)	0.66776 (11)	0.0329 (4)
H7	0.8813	0.0435	0.7134	0.040*
C8	0.83674 (19)	−0.1226 (2)	0.61733 (14)	0.0474 (5)
H8A	0.7591	−0.1418	0.5804	0.071*
H8B	0.8484	−0.2037	0.6601	0.071*
H8C	0.9141	−0.1159	0.5792	0.071*
C9	0.78835 (17)	0.27527 (19)	0.79723 (10)	0.0336 (4)
H9A	0.7509	0.1921	0.8318	0.040*
H9B	0.8826	0.2542	0.7886	0.040*
C10	0.7754 (2)	0.4189 (2)	0.85282 (13)	0.0527 (6)
H10A	0.8171	0.5011	0.8211	0.079*
H10B	0.8182	0.4052	0.9109	0.079*
H10C	0.6825	0.4415	0.8617	0.079*
C11	0.90159 (17)	0.36412 (18)	0.59040 (11)	0.0330 (4)
C12	1.13479 (19)	0.3331 (3)	0.60806 (15)	0.0539 (5)
H12A	1.1316	0.2327	0.5833	0.081*
H12B	1.2024	0.3380	0.6546	0.081*
H12C	1.1556	0.4038	0.5606	0.081*
C13	0.49022 (18)	0.2418 (2)	0.76527 (12)	0.0412 (4)
H13A	0.4012	0.2818	0.7609	0.062*
H13B	0.5190	0.2427	0.8277	0.062*
H13C	0.4911	0.1399	0.7428	0.062*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0292 (7)	0.0591 (8)	0.0422 (7)	−0.0029 (6)	−0.0038 (5)	−0.0015 (6)
O2	0.0510 (8)	0.0719 (10)	0.0358 (7)	0.0004 (7)	0.0024 (6)	−0.0108 (6)
O3	0.0444 (7)	0.0371 (7)	0.0460 (7)	0.0040 (5)	−0.0255 (6)	−0.0061 (5)
N1	0.0332 (8)	0.0249 (7)	0.0294 (7)	0.0039 (6)	−0.0106 (6)	−0.0051 (6)
N2	0.0282 (7)	0.0297 (7)	0.0272 (7)	0.0019 (5)	−0.0028 (5)	−0.0010 (5)
C1	0.0257 (8)	0.0274 (8)	0.0231 (7)	−0.0013 (6)	−0.0039 (6)	0.0004 (6)
C2	0.0271 (8)	0.0264 (8)	0.0240 (8)	0.0015 (6)	−0.0054 (6)	−0.0010 (6)
C3	0.0325 (9)	0.0247 (8)	0.0304 (8)	−0.0041 (6)	−0.0036 (7)	−0.0012 (6)
C4	0.0399 (10)	0.0278 (8)	0.0344 (9)	−0.0010 (7)	−0.0061 (7)	0.0072 (7)
C5	0.0293 (9)	0.0266 (8)	0.0324 (8)	0.0053 (6)	−0.0091 (7)	−0.0007 (6)
C6	0.0290 (9)	0.0307 (8)	0.0274 (8)	0.0005 (7)	−0.0064 (6)	0.0014 (6)
C7	0.0300 (9)	0.0315 (9)	0.0372 (9)	0.0038 (7)	−0.0093 (7)	−0.0035 (7)
C8	0.0379 (10)	0.0421 (10)	0.0620 (13)	0.0112 (8)	−0.0104 (9)	−0.0155 (9)
C9	0.0397 (10)	0.0355 (9)	0.0256 (8)	0.0025 (7)	−0.0101 (7)	−0.0026 (7)
C10	0.0722 (14)	0.0507 (12)	0.0352 (10)	0.0086 (10)	−0.0186 (10)	−0.0141 (9)
C11	0.0363 (10)	0.0293 (8)	0.0335 (9)	−0.0051 (7)	−0.0018 (7)	0.0017 (7)
C12	0.0353 (11)	0.0666 (13)	0.0598 (13)	0.0065 (9)	0.0047 (9)	0.0047 (10)
C13	0.0376 (10)	0.0489 (11)	0.0371 (9)	−0.0018 (8)	0.0068 (7)	0.0000 (8)

Geometric parameters (Å, º) top

O1—C11	1.336 (3)	C5—C6	1.509 (3)
O1—C12	1.438 (3)	C5—H5	0.9800
O2—C11	1.204 (2)	C7—C8	1.498 (3)
O3—C6	1.234 (2)	C7—H7	0.9300
N1—C6	1.349 (3)	C8—H8A	0.9600
N1—C1	1.421 (3)	C8—H8B	0.9600
N1—H1	0.89 (2)	C8—H8C	0.9600
N2—C13	1.460 (3)	C9—C10	1.516 (3)
N2—C5	1.461 (2)	C9—H9A	0.9700
N2—C2	1.478 (3)	C9—H9B	0.9700
C1—C7	1.327 (3)	C10—H10A	0.9600
C1—C2	1.536 (2)	C10—H10B	0.9600
C2—C9	1.535 (2)	C10—H10C	0.9600
C2—C3	1.573 (2)	C12—H12A	0.9600
C3—C11	1.503 (3)	C12—H12B	0.9600
C3—C4	1.535 (3)	C12—H12C	0.9600
C3—H3	0.9800	C13—H13A	0.9600
C4—C5	1.540 (3)	C13—H13B	0.9600
C4—H4A	0.9700	C13—H13C	0.9600
C4—H4B	0.9700

C11—O1—C12	116.64 (17)	C1—C7—C8	127.49 (16)
C6—N1—C1	124.81 (15)	C1—C7—H7	116.3
C6—N1—H1	114.7 (12)	C8—C7—H7	116.3
C1—N1—H1	120.3 (12)	C7—C8—H8A	109.5
C13—N2—C5	114.90 (15)	C7—C8—H8B	109.5
C13—N2—C2	116.32 (16)	H8A—C8—H8B	109.5
C5—N2—C2	103.16 (14)	C7—C8—H8C	109.5
C7—C1—N1	120.81 (16)	H8A—C8—H8C	109.5
C7—C1—C2	124.61 (15)	H8B—C8—H8C	109.5
N1—C1—C2	114.53 (13)	C10—C9—C2	114.83 (14)
N2—C2—C9	110.96 (15)	C10—C9—H9A	108.6
N2—C2—C1	110.95 (13)	C2—C9—H9A	108.6
C9—C2—C1	112.15 (12)	C10—C9—H9B	108.6
N2—C2—C3	98.63 (14)	C2—C9—H9B	108.6
C9—C2—C3	113.70 (14)	H9A—C9—H9B	107.5
C1—C2—C3	109.71 (14)	C9—C10—H10A	109.5
C11—C3—C4	114.38 (17)	C9—C10—H10B	109.5
C11—C3—C2	114.08 (14)	H10A—C10—H10B	109.5
C4—C3—C2	104.27 (15)	C9—C10—H10C	109.5
C11—C3—H3	107.9	H10A—C10—H10C	109.5
C4—C3—H3	107.9	H10B—C10—H10C	109.5
C2—C3—H3	107.9	O2—C11—O1	122.95 (18)
C3—C4—C5	103.97 (16)	O2—C11—C3	126.01 (17)
C3—C4—H4A	111.0	O1—C11—C3	111.03 (17)
C5—C4—H4A	111.0	O1—C12—H12A	109.5
C3—C4—H4B	111.0	O1—C12—H12B	109.5
C5—C4—H4B	111.0	H12A—C12—H12B	109.5
H4A—C4—H4B	109.0	O1—C12—H12C	109.5
N2—C5—C6	111.40 (13)	H12A—C12—H12C	109.5
N2—C5—C4	102.95 (15)	H12B—C12—H12C	109.5
C6—C5—C4	108.93 (14)	N2—C13—H13A	109.5
N2—C5—H5	111.1	N2—C13—H13B	109.5
C6—C5—H5	111.1	H13A—C13—H13B	109.5
C4—C5—H5	111.1	N2—C13—H13C	109.5
O3—C6—N1	122.59 (17)	H13A—C13—H13C	109.5
O3—C6—C5	122.57 (14)	H13B—C13—H13C	109.5
N1—C6—C5	114.83 (15)

C6—N1—C1—C7	−174.78 (15)	C2—N2—C5—C6	68.66 (15)
C6—N1—C1—C2	2.8 (2)	C13—N2—C5—C4	−175.55 (13)
C13—N2—C2—C9	−62.39 (17)	C2—N2—C5—C4	−47.93 (17)
C5—N2—C2—C9	170.88 (12)	C3—C4—C5—N2	23.33 (15)
C13—N2—C2—C1	63.00 (17)	C3—C4—C5—C6	−95.00 (15)
C5—N2—C2—C1	−63.73 (15)	C1—N1—C6—O3	−179.98 (15)
C13—N2—C2—C3	178.04 (12)	C1—N1—C6—C5	0.8 (2)
C5—N2—C2—C3	51.31 (13)	N2—C5—C6—O3	142.49 (16)
C7—C1—C2—N2	−152.27 (16)	C4—C5—C6—O3	−104.6 (2)
N1—C1—C2—N2	30.24 (18)	N2—C5—C6—N1	−38.29 (19)
C7—C1—C2—C9	−27.6 (2)	C4—C5—C6—N1	74.6 (2)
N1—C1—C2—C9	154.96 (14)	N1—C1—C7—C8	2.9 (3)
C7—C1—C2—C3	99.8 (2)	C2—C1—C7—C8	−174.41 (17)
N1—C1—C2—C3	−77.69 (19)	N2—C2—C9—C10	−49.66 (19)
N2—C2—C3—C11	−160.56 (12)	C1—C2—C9—C10	−174.36 (15)
C9—C2—C3—C11	81.93 (19)	C3—C2—C9—C10	60.4 (2)
C1—C2—C3—C11	−44.55 (17)	C12—O1—C11—O2	0.5 (2)
N2—C2—C3—C4	−35.10 (15)	C12—O1—C11—C3	−179.45 (15)
C9—C2—C3—C4	−152.61 (13)	C4—C3—C11—O2	−15.9 (2)
C1—C2—C3—C4	80.91 (16)	C2—C3—C11—O2	104.03 (19)
C11—C3—C4—C5	132.86 (15)	C4—C3—C11—O1	164.10 (13)
C2—C3—C4—C5	7.59 (15)	C2—C3—C11—O1	−75.98 (17)
C13—N2—C5—C6	−58.97 (18)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O3ⁱ	0.89 (2)	2.10 (2)	2.975 (3)	170.9 (16)

Symmetry code: (i) −x+1, −y, −z+1.

Acknowledgements

YY gratefully acknowledges a studentship from The University of Manchester.

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