(+)-(4R,5S)-4-Methyl-5-phenyl-3-[2(S)-phenyl­propion­yl]oxazolidin-2-one

Coumbarides, G.S.; Eames, J.; Motevalli, M.; Malatesti, N.; Yohannes, Y.

doi:10.1107/S1600536806031813

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 62| Part 9| September 2006| Pages o4032-o4034

https://doi.org/10.1107/S1600536806031813

(+)-(4R,5S)-4-Methyl-5-phenyl-3-[2(S)-phenylpropionyl]oxazolidin-2-one

Gregory S. Coumbarides,^a Jason Eames,^b ^* Majid Motevalli,^a Nela Malatesti ^c and Yonas Yohannes ^a

^aDepartment of Chemistry, Queen Mary, University of London, Mile End Road, London E1 4NS, England, ^bDepartment of Chemistry, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, England, and ^cDepartment of Chemistry, J. J. Strossmayer University of Osijek, Trg Sv. Trojstva 3, Osijek 31000, Croatia
^*Correspondence e-mail: j.eames@hull.ac.uk

(Received 26 June 2006; accepted 12 August 2006; online 23 August 2006)

In the title compound, C₁₉H₁₉NO₃, formed from enantiomerically pure (+)-(4R,5S)-4-methyl-5-phenyl-2-oxazolidinone and racemic 2-phenylpropanoyl chloride, the two carbonyl groups are oriented anti to each other, and the two methyl groups are oriented anti to each other.

Comment

The development of predictable and efficient resolution methodology is becoming increasingly important for academia and industry alike. With this aim in mind, we have recently focused our attention on the resolution of profens (Sonawane et al., 1992 ; Fuji et al., 1989 ; Larsen et al., 1989 ), such as ibuprofen (Alper & Hamel, 1990 ; Piccolo et al., 1991 ) and naproxen (Stille & Parrinello, 1993 ; Ohta et al., 1987 ; Kumar et al., 1991 ), using a novel parallel kinetic resolution methodology (Coumbarides, Dingjan, Eames, Flinn et al., 2006 ; Coumbarides, Dingjan et al., 2005 ; Coumbarides, Eames et al., 2005 ). For this project, we were required to determine the relative and absolute configurations of a series of related profen adducts derived from (+)-(4R,5S)-4-methyl-5-phenyl-2-oxazolidinone, (1). The compounds were obtained in each case by addition of racemic 2-(R¹)-propanoyl chloride (where R¹ is a substituent group) to a solution of lithiated oxazolidinone, the latter being derived from the addition of n-BuLi to the (R,S)-oxazolidinone (1) in tetrahydrofuran at 195 K (see reaction scheme).

The reaction provided in each case a separable mixture of diastereoisomeric anti–syn and syn–syn oxazolidinone adducts. In the following series of reports (Chavda et al. 2006a ,b ; Coumbarides, Dingjan, Eames, Motevalli & Malatesti et al., 2006 ; Chavda et al., 2006 ; Coumbarides, Eames, Motevalli, Malatesti & Yohannes, 2006 ), we describe the crystal structures of six of these related compounds.

With R¹ = C₆H₅, the reaction shown in the scheme yielded the anti–syn and syn–syn diastereomers in 23 and 25% yields, respectively. The title compound, (I), is the syn–syn diastereomer (Fig. 1).

In the crystal structure of (I), the five-membered ring displays a twist conformation in which atoms O1, O2, N1 and C3 lie in an approximate plane, and C1 and C2 lie, respectively, 0.248 (3) Å above and 0.262 (3) Å below that plane. The two methyl groups (C4 and C19) lie anti to each other, on either side of the central five-membered ring. The carbonyl groups (C3=O2 and C11=O3) are also oriented anti to each other [torsion angle O3—C11—N1—C3 = −169.3 (2)°], avoiding electrostatic repulsion between the two O atoms. The electrostatic factor also appears to be important for determining the molecular packing (Fig. 2), whereby adjacent molecules approach each other in a `side-on' manner. The shortest intermolecular contacts to each O atom are made by H atoms [H4A⋯O2ⁱ = 2.66 Å, H2⋯O3ⁱⁱ = 2.63 Å; symmetry codes: (i) 1 − x, $[{1\over 2}]$ + y, 2 − z; (ii) 1 − x, − $[{1\over 2}]$ + y, 1 − z].

Figure 1
The molecular structure of (I)

, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted.

Figure 2
The crystal packing of (I), viewed along the b axis. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted.

Experimental

The following procedure is representative for the reaction sequence depicted in the reaction scheme. n-Butyllithium (6.33 ml, 2.5 M in hexanes, 15.8 mmol) was added dropwise to a stirred solution of (R,S)-oxazolidinone, (1) (2 g, 11.3 mmol), in tetrahydrofuran (20 ml) at 195 K. The resulting solution was stirred at 195 K for 1 h. A solution of racemic 2-phenylpropanoyl chloride (1.90 g, 11.3 mmol) in tetrahydrofuran (5 ml) was added dropwise and the resulting solution was stirred at 195 K for 2 h. The reaction was quenched by the addition of water (10 ml), extracted with CH₂Cl₂ (3 × 10 ml) and dried over MgSO₄. The combined organic layers were evaporated under reduced pressure. The crude residue was purified by flash column chromatography on silica gel, eluting with light petroleum (b.p. 313–333 K)/diethyl ether (7:3), to give a separable diastereoisomeric mixture (in the approximate ratio anti–syn:syn–syn 50:50) of the title compound; anti–syn diastereomer (0.80 g, 23%), syn–syn diastereomer (0.87 g, 25%). The latter was obtained as colourless crystals suitable for X-ray analysis [m.p. 394–396 K, R_F 0.63 (light petroleum (b.p 313–333 K)/diethyl ether, 1:1].

Spectroscopic analysis for (I): [α]²⁰_D = 122.9 (CHCl₃, 293 K, concentration 0.81 g per 100 ml); IR (CHCl₃, ν_max, cm⁻¹): 1774 (C=O), 1701 (C=O); ¹H NMR (250 MHz, CDCl₃): δ 7.40–7.17 (10H, m, 10 × CH; Ph_a and Ph_b), 5.64 (1H, d, J = 7.2 Hz, OCHPh), 5.08 (1H, q, J = 7.1 Hz, PhCH), 4.82 (1H, m, CHN), 1.51 (3H, d, J = 7.1 Hz, CH₃CHCO), 0.74 (3H, d, J = 6.6 Hz, CH₃CHN); ¹³C NMR (62.9 MHz; CDCl₃): δ 174.3 (NC=O), 152.5 (OC=O), 140.3 (i-C; Ph_a), 133.5 (i-C; Ph_b), 128.9, 128.8, 128.6, 128.1, 127.1, 125.7 (6 × CH; Ph_a and Ph_b), 78.8 (OCHPh), 54.7 (CH₃CHO), 43.6 (PhCH), 19.4 (CH₃), 14.1 (CH₃); MS m/z: MH⁺ 310.1460; C₁₉H₂₀NO₃ requires 310.1443.

Crystal data

C₁₉H₁₉NO₃
M_r = 309.35
Monoclinic, P 2₁
a = 14.757 (2) Å
b = 6.069 (2) Å
c = 9.109 (4) Å
β = 104.02 (6)°
V = 791.5 (5) Å³
Z = 2
D_x = 1.298 Mg m⁻³
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 160 (2) K
Prism, colourless
0.40 × 0.30 × 0.20 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
ω/2θ scans
Absorption correction: none
1623 measured reflections
1521 independent reflections
1449 reflections with I > 2σ(I)
R_int = 0.009
θ_max = 25.1°
4 standard reflections every 100 reflections intensity decay: none

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.075
S = 1.06
1521 reflections
210 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0487P)² + 0.119P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.23 e Å⁻³

H atoms were placed in geometrically idealised positions and constrained to ride on their parent atoms, with C—H = 0.95–1.00 Å and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C). The methyl groups were allowed to rotate about their local threefold axes. In the absence of significant anomalous scattering effects, the few measured Friedel pairs were merged. The absolute configuration is assigned on the basis of the known configuration of (1) (Evans et al., 1985 ).

Data collection: CAD-4-PC (Enraf–Nonius, 1994 ); cell refinement: CAD-4-PC; data reduction: XCAD4 (Harms & Wocadlo, 1995 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536806031813/bi2029sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536806031813/bi2029Isup2.hkl

Computing details top

Data collection: CAD-4-PC (Enraf–Nonius, 1994); cell refinement: CAD-4-PC; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

(+)-(4R,5S)-4-Methyl-5-phenyl-3-[-2(S)-phenylpropionyl]- oxazolidin-2-one top

Crystal data top

C₁₉H₁₉NO₃	F(000) = 328
M_r = 309.35	D_x = 1.298 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 25 reflections
a = 14.757 (2) Å	θ = 9.7–13.0°
b = 6.069 (2) Å	µ = 0.09 mm⁻¹
c = 9.109 (4) Å	T = 160 K
β = 104.02 (6)°	Prism, colourless
V = 791.5 (5) Å³	0.40 × 0.30 × 0.20 mm
Z = 2

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.009
Radiation source: fine-focus sealed tube	θ_max = 25.1°, θ_min = 1.4°
Graphite monochromator	h = −16→17
ω/2θ scans	k = 0→7
1623 measured reflections	l = −10→0
1521 independent reflections	4 standard reflections every 100 reflections
1449 reflections with I > 2σ(I)	intensity decay: none

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.028	H-atom parameters constrained
wR(F²) = 0.075	w = 1/[σ²(F_o²) + (0.0487P)² + 0.119P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
1521 reflections	Δρ_max = 0.13 e Å⁻³
210 parameters	Δρ_min = −0.23 e Å⁻³
1 restraint	Absolute structure: assigned on the basis of known starting material
Primary atom site location: structure-invariant direct methods

Special details top

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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

- 3.1511 (0.0161) x + 5.4484 (0.0064) y + 3.8763 (0.0094) z = 1.0707 (0.0091)

* 0.0004 (0.0005) O1 * 0.0006 (0.0007) O2 * 0.0004 (0.0005) N1 * -0.0014 (0.0018) C3 0.2480 (0.0033) C1 - 0.2624 (0.0030) C2

Rms deviation of fitted atoms = 0.0008

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 > 2σ(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 (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.49725 (10)	−0.0506 (3)	0.75171 (16)	0.0223 (4)
O1	0.36438 (9)	−0.1645 (3)	0.80375 (14)	0.0288 (3)
O2	0.49467 (11)	−0.2176 (3)	0.98430 (16)	0.0292 (3)
O3	0.61111 (9)	0.1127 (3)	0.66406 (15)	0.0304 (4)
C1	0.42346 (13)	0.0405 (3)	0.6275 (2)	0.0228 (4)
H1A	0.4394	0.0154	0.5282	0.027*
C2	0.34228 (13)	−0.1103 (3)	0.6418 (2)	0.0241 (4)
H2A	0.3448	−0.2483	0.5830	0.029*
C3	0.45794 (13)	−0.1511 (4)	0.8604 (2)	0.0240 (4)
C4	0.40795 (14)	0.2829 (4)	0.6495 (2)	0.0290 (5)
H4A	0.4663	0.3634	0.6553	0.043*
H4B	0.3879	0.3045	0.7435	0.043*
H4C	0.3596	0.3383	0.5639	0.043*
C5	0.24509 (13)	−0.0169 (4)	0.5956 (2)	0.0249 (4)
C6	0.19350 (13)	−0.0559 (4)	0.4484 (2)	0.0271 (4)
H6A	0.2190	−0.1435	0.3818	0.033*
C7	0.10495 (14)	0.0336 (4)	0.3992 (2)	0.0317 (5)
H7A	0.0700	0.0079	0.2985	0.038*
C8	0.06702 (14)	0.1605 (4)	0.4963 (2)	0.0343 (5)
H8A	0.0064	0.2221	0.4619	0.041*
C9	0.11767 (14)	0.1972 (4)	0.6431 (3)	0.0359 (5)
H9A	0.0916	0.2836	0.7096	0.043*
C10	0.20617 (14)	0.1087 (4)	0.6934 (2)	0.0316 (5)
H10A	0.2405	0.1333	0.7946	0.038*
C11	0.59155 (12)	−0.0054 (3)	0.7605 (2)	0.0227 (4)
C12	0.66371 (13)	−0.1199 (4)	0.8843 (2)	0.0241 (4)
H12A	0.6446	−0.1038	0.9818	0.029*
C13	0.75975 (13)	−0.0172 (3)	0.9030 (2)	0.0241 (4)
C14	0.81250 (13)	−0.0474 (4)	0.7946 (2)	0.0275 (4)
H14A	0.7872	−0.1311	0.7060	0.033*
C15	0.90074 (13)	0.0432 (4)	0.8157 (2)	0.0311 (5)
H15A	0.9355	0.0216	0.7417	0.037*
C16	0.93844 (13)	0.1653 (4)	0.9444 (2)	0.0335 (5)
H16A	0.9991	0.2273	0.9592	0.040*
C17	0.88689 (14)	0.1966 (4)	1.0521 (2)	0.0349 (5)
H17A	0.9124	0.2813	1.1402	0.042*
C18	0.79813 (14)	0.1048 (4)	1.0317 (2)	0.0302 (5)
H18A	0.7638	0.1258	1.1063	0.036*
C19	0.66362 (14)	−0.3671 (4)	0.8450 (2)	0.0311 (5)
H19D	0.6039	−0.4327	0.8507	0.047*
H19A	0.7146	−0.4411	0.9171	0.047*
H19B	0.6723	−0.3845	0.7423	0.047*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0212 (7)	0.0260 (9)	0.0195 (7)	−0.0001 (7)	0.0047 (6)	0.0030 (7)
O1	0.0235 (7)	0.0334 (8)	0.0295 (7)	−0.0010 (7)	0.0067 (5)	0.0069 (7)
O2	0.0333 (7)	0.0314 (8)	0.0229 (7)	0.0022 (7)	0.0065 (5)	0.0082 (7)
O3	0.0266 (7)	0.0378 (9)	0.0270 (7)	−0.0020 (7)	0.0071 (5)	0.0087 (7)
C1	0.0219 (9)	0.0297 (10)	0.0163 (9)	0.0025 (8)	0.0035 (7)	0.0015 (8)
C2	0.0254 (10)	0.0244 (11)	0.0217 (9)	−0.0001 (8)	0.0039 (7)	−0.0035 (8)
C3	0.0251 (9)	0.0205 (9)	0.0271 (10)	0.0007 (8)	0.0081 (8)	−0.0011 (9)
C4	0.0274 (10)	0.0289 (11)	0.0284 (10)	−0.0003 (9)	0.0023 (8)	0.0060 (9)
C5	0.0226 (9)	0.0239 (10)	0.0283 (9)	−0.0035 (8)	0.0066 (7)	−0.0001 (9)
C6	0.0253 (9)	0.0266 (11)	0.0298 (9)	−0.0039 (9)	0.0072 (8)	−0.0026 (9)
C7	0.0264 (10)	0.0334 (12)	0.0320 (10)	−0.0044 (9)	0.0004 (8)	−0.0008 (10)
C8	0.0239 (9)	0.0338 (12)	0.0445 (11)	0.0018 (10)	0.0071 (8)	0.0047 (11)
C9	0.0299 (10)	0.0377 (13)	0.0431 (11)	0.0031 (10)	0.0147 (9)	−0.0054 (11)
C10	0.0290 (10)	0.0373 (13)	0.0288 (10)	0.0006 (10)	0.0076 (8)	−0.0030 (10)
C11	0.0234 (9)	0.0247 (11)	0.0201 (9)	0.0007 (8)	0.0053 (7)	−0.0005 (9)
C12	0.0232 (9)	0.0273 (11)	0.0213 (9)	0.0013 (8)	0.0045 (7)	0.0018 (8)
C13	0.0236 (9)	0.0222 (10)	0.0241 (9)	0.0051 (8)	0.0014 (7)	0.0025 (9)
C14	0.0260 (9)	0.0297 (11)	0.0249 (9)	0.0017 (9)	0.0028 (7)	−0.0011 (9)
C15	0.0259 (10)	0.0333 (11)	0.0343 (11)	0.0037 (9)	0.0077 (8)	0.0034 (10)
C16	0.0246 (9)	0.0299 (11)	0.0424 (11)	−0.0010 (10)	0.0013 (8)	0.0012 (11)
C17	0.0311 (10)	0.0329 (13)	0.0362 (11)	−0.0017 (9)	−0.0007 (9)	−0.0089 (10)
C18	0.0288 (10)	0.0315 (13)	0.0290 (10)	0.0041 (9)	0.0046 (8)	−0.0037 (9)
C19	0.0303 (10)	0.0255 (11)	0.0367 (11)	0.0013 (9)	0.0067 (8)	−0.0001 (10)

Geometric parameters (Å, º) top

N1—C11	1.402 (2)	C8—H8A	0.950
N1—C3	1.403 (3)	C9—C10	1.384 (3)
N1—C1	1.475 (2)	C9—H9A	0.950
O1—C3	1.354 (2)	C10—H10A	0.950
O1—C2	1.469 (2)	C11—C12	1.519 (3)
O2—C3	1.197 (2)	C12—C13	1.520 (3)
O3—C11	1.222 (2)	C12—C19	1.542 (3)
C1—C4	1.510 (3)	C12—H12A	1.000
C1—C2	1.538 (3)	C13—C18	1.386 (3)
C1—H1A	1.000	C13—C14	1.409 (3)
C2—C5	1.504 (3)	C14—C15	1.383 (3)
C2—H2A	1.000	C14—H14A	0.950
C4—H4A	0.980	C15—C16	1.385 (3)
C4—H4B	0.980	C15—H15A	0.950
C4—H4C	0.980	C16—C17	1.392 (3)
C5—C6	1.393 (3)	C16—H16A	0.950
C5—C10	1.397 (3)	C17—C18	1.394 (3)
C6—C7	1.385 (3)	C17—H17A	0.950
C6—H6A	0.950	C18—H18A	0.950
C7—C8	1.389 (3)	C19—H19D	0.980
C7—H7A	0.950	C19—H19A	0.980
C8—C9	1.383 (3)	C19—H19B	0.980

C11—N1—C3	128.28 (16)	C8—C9—H9A	119.9
C11—N1—C1	120.59 (16)	C10—C9—H9A	119.9
C3—N1—C1	110.48 (14)	C9—C10—C5	120.09 (19)
C3—O1—C2	109.10 (15)	C9—C10—H10A	120.0
N1—C1—C4	111.80 (18)	C5—C10—H10A	120.0
N1—C1—C2	99.06 (15)	O3—C11—N1	118.56 (17)
C4—C1—C2	115.00 (17)	O3—C11—C12	123.87 (16)
N1—C1—H1A	110.2	N1—C11—C12	117.44 (17)
C4—C1—H1A	110.2	C11—C12—C13	111.25 (17)
C2—C1—H1A	110.2	C11—C12—C19	108.15 (16)
O1—C2—C5	109.26 (16)	C13—C12—C19	111.92 (17)
O1—C2—C1	103.31 (15)	C11—C12—H12A	108.5
C5—C2—C1	117.49 (17)	C13—C12—H12A	108.5
O1—C2—H2A	108.8	C19—C12—H12A	108.5
C5—C2—H2A	108.8	C18—C13—C14	118.69 (18)
C1—C2—H2A	108.8	C18—C13—C12	119.50 (18)
O2—C3—O1	121.74 (19)	C14—C13—C12	121.78 (18)
O2—C3—N1	129.92 (18)	C15—C14—C13	120.80 (19)
O1—C3—N1	108.34 (16)	C15—C14—H14A	119.6
C1—C4—H4A	109.5	C13—C14—H14A	119.6
C1—C4—H4B	109.5	C14—C15—C16	120.12 (19)
H4A—C4—H4B	109.5	C14—C15—H15A	119.9
C1—C4—H4C	109.5	C16—C15—H15A	119.9
H4A—C4—H4C	109.5	C15—C16—C17	119.58 (19)
H4B—C4—H4C	109.5	C15—C16—H16A	120.2
C6—C5—C10	119.57 (18)	C17—C16—H16A	120.2
C6—C5—C2	117.84 (18)	C16—C17—C18	120.5 (2)
C10—C5—C2	122.59 (17)	C16—C17—H17A	119.7
C7—C6—C5	119.84 (19)	C18—C17—H17A	119.7
C7—C6—H6A	120.1	C13—C18—C17	120.31 (19)
C5—C6—H6A	120.1	C13—C18—H18A	119.8
C6—C7—C8	120.37 (19)	C17—C18—H18A	119.8
C6—C7—H7A	119.8	C12—C19—H19D	109.5
C8—C7—H7A	119.8	C12—C19—H19A	109.5
C9—C8—C7	119.9 (2)	H19D—C19—H19A	109.5
C9—C8—H8A	120.1	C12—C19—H19B	109.5
C7—C8—H8A	120.1	H19D—C19—H19B	109.5
C8—C9—C10	120.2 (2)	H19A—C19—H19B	109.5

C11—N1—C1—C4	−75.0 (2)	C7—C8—C9—C10	0.3 (4)
C3—N1—C1—C4	96.5 (2)	C8—C9—C10—C5	0.5 (4)
C11—N1—C1—C2	163.36 (17)	C6—C5—C10—C9	−1.3 (3)
C3—N1—C1—C2	−25.2 (2)	C2—C5—C10—C9	177.6 (2)
C3—O1—C2—C5	−152.44 (17)	C3—N1—C11—O3	−169.1 (2)
C3—O1—C2—C1	−26.6 (2)	C1—N1—C11—O3	0.8 (3)
N1—C1—C2—O1	29.82 (18)	C3—N1—C11—C12	15.0 (3)
C4—C1—C2—O1	−89.5 (2)	C1—N1—C11—C12	−175.22 (18)
N1—C1—C2—C5	150.16 (16)	O3—C11—C12—C13	17.3 (3)
C4—C1—C2—C5	30.9 (3)	N1—C11—C12—C13	−166.97 (16)
C2—O1—C3—O2	−169.2 (2)	O3—C11—C12—C19	−106.0 (2)
C2—O1—C3—N1	11.1 (2)	N1—C11—C12—C19	69.7 (2)
C11—N1—C3—O2	1.1 (4)	C11—C12—C13—C18	109.8 (2)
C1—N1—C3—O2	−169.5 (2)	C19—C12—C13—C18	−129.1 (2)
C11—N1—C3—O1	−179.17 (19)	C11—C12—C13—C14	−72.0 (2)
C1—N1—C3—O1	10.2 (2)	C19—C12—C13—C14	49.1 (2)
O1—C2—C5—C6	−148.48 (18)	C18—C13—C14—C15	−0.2 (3)
C1—C2—C5—C6	94.3 (2)	C12—C13—C14—C15	−178.4 (2)
O1—C2—C5—C10	32.6 (3)	C13—C14—C15—C16	0.0 (3)
C1—C2—C5—C10	−84.6 (2)	C14—C15—C16—C17	−0.2 (3)
C10—C5—C6—C7	1.3 (3)	C15—C16—C17—C18	0.5 (4)
C2—C5—C6—C7	−177.71 (19)	C14—C13—C18—C17	0.5 (3)
C5—C6—C7—C8	−0.5 (3)	C12—C13—C18—C17	178.76 (19)
C6—C7—C8—C9	−0.3 (4)	C16—C17—C18—C13	−0.7 (3)

Acknowledgements

We are grateful to the EPSRC and Queen Mary, University of London, for a studentship to YY, the Royal Society and the University of London Central Research Fund for financial support to JE, and the EPSRC National Mass Spectrometry Service (Swansea) for accurate mass determination.

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