1-tert-Butyl 2-ethyl 5-chloro-3-(2-furo­yl)-1H-indole-1,2-dicarboxyl­ate

Hassam, M.; Smith, V.J.

doi:10.1107/S1600536813005059

organic compounds

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ISSN: 2056-9890

Volume 69| Part 3| March 2013| Page o446

doi:10.1107/S1600536813005059

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1-tert-Butyl 2-ethyl 5-chloro-3-(2-furoyl)-1H-indole-1,2-dicarboxylate

Mohammad Hassam ^a ^* and Vincent J. Smith ^a

^aDepartment of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
^*Correspondence e-mail: hassam@sun.ac.za

(Received 20 February 2013; accepted 20 February 2013; online 28 February 2013)

In the title compound, C₂₁H₂₀ClNO₆, the furan moiety is located above the mean plane of the indole ring and displays rotational disorder (i.e. rotation through 180°); the site occupancy of the major component is 0.809 (6). In the crystal, C—H⋯O interactions link the molecules into chains which run parallel to the b axis.

Related literature

For background to the use of indoles as scaffolds in the synthesis of HIV-agents, see: Hassam et al. (2012 ) and for a recent review on stages of non-nucleoside reverse transcriptase inhibitors, see: Reynolds et al. (2012 ). For the crystal structures of closely related compounds, see: Beddoes et al. (1986 ), Hassam & Smith (2012 , 2013 ).

Experimental

Crystal data

C₂₁H₂₀ClNO₆
M_r = 417.83
Monoclinic, P 2₁ /c
a = 9.8354 (8) Å
b = 8.0938 (7) Å
c = 25.435 (2) Å
β = 99.344 (1)°
V = 1997.9 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 100 K
0.32 × 0.32 × 0.24 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.930, T_max = 0.947
11690 measured reflections
4483 independent reflections
3877 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.084
S = 1.05
4483 reflections
279 parameters
8 restraints
H-atom parameters constrained
Δρ_max = 0.29 e Å⁻³
Δρ_min = −0.38 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13A—H13A⋯O5ⁱ	0.95	2.37	3.187 (3)	144
Symmetry code: (i) $[-x+2, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ; Atwood & Barbour, 2003 ); software used to prepare material for publication: X-SEED.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813005059/zl2535sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813005059/zl2535Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813005059/zl2535Isup3.cml

checkCIF report

Comment top

Ethyl-5-chloro-1H-indole-2-carboxylate has been employed as a building block in the synthesis of various anti-HIV active molecules particularly in the search for novel non-nucleoside reverse transcriptase inhibitors (Hassam et al. 2012, Reynolds et al. 2012). Protection on the indole NH of ethyl 5-chloro-3-(2-furoyl)-1H-indole-2-carboxylate was carried out with di-tert-butyl-dicarbonate using 4-dimethylaminopyridine as a catalytic base.

The title compound, C₂₁H₂₀ClNO₆, crystallizes with one molecule in the asymmetric unit (Fig. 1). The furan group is disordered over two positions with major (A) and minor (B) components in a 0.809 (6):0.191 (6) ratio. The dihedral angles between the mean planes of the 5-chloro indole ring (Cl1/N1/C1—C8) and the disordered furan rings (O6A/C10/C11A/C13A and O6B/C10/C11B/C13B) are 58.01 (13)° and 59.70 (68)°, respectively. The angles between the mean planes of the indole ring and the N-tert-butyloxy, ethyl ester and the ketone groups are 26.90 (04)°, 55.71 (04)° and 46.18 (05)°, respectively. The torsion angles of O5/C9/C10/O6A and O5/C9/C10/O6B are 12.1 (3)° and -157.5 (1)°, respectively, thereby describing the major component in a cis conformation and the minor component in a trans conformation. Molecular packing shows the molecules being connected via weak C13A—H13A···O5 intermolecular interactions that link molecules into chains which run parallel to the b axis (Fig. 2, Table 1).

Related literature top

For background to the use of indoles as scaffolds in the synthesis of HIV-agents, see: Hassam et al. (2012) and for a recent review on stages of non-nucleoside reverse transcriptase inhibitors, see: Reynolds et al. (2012). For the crystal structures of aclosely related compounds, see: Beddoes et al. (1986), Hassam & Smith (2012), Hassam & Smith (2013).

Experimental top

A catalytic amount of 4-dimethylaminopyridine was added to a solution of ethyl 5-chloro-3-(2-furoyl)-1H-indole-2-carboxylate (1.00 g, 3.14 mmol) in THF (20 ml), followed by the addition of di-tert-butyl dicarbonate (1.10 g, 5.04 mmol). The reaction mixture was then stirred at room temperature for 2 h. The solvent was removed under vacuum and the resulting residue was recrystallized from a hexane/dichloromethane solvent (4:1) to obtain the title compound as a colourless crystalline material (1.14 g, 87%). ¹H NMR (300 MHz, CDCl₃) δ 8.08 (dd, J = 9.0, 0.5 Hz, 1H), 7.74 (dd, J = 2.1, 0.5 Hz, 1H), 7.65 (dd, J = 1.7, 0.8 Hz, 1H), 7.39 (dd, J = 9.0, 2.1 H, 1H), 7.20 (dd, J = 3.6, 0.8 Hz, 1H), 6.59 (dd, J = 3.6, 1.7 H, 1H), 4.17 (q, J = 7.2 Hz, 2H), 1.63 (s, 9H), 1.15 (t, J = 7.2 Hz, 3H). ¹³C NMR (75 Hz, CDCl₃) 177.17, 161.30, 152.79, 148. 39, 147.33, 134.24, 133.16, 130.17, 127.59, 127.36, 121.28, 120.65, 119.81, 116.35, 112.80, 86.62, 62.43, 27.87, 13.78. HRMS calculated for C₂₁H₂₁ClNO₆ [M+H]⁺, 418.1057 found 418.53.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001; Atwood & Barbour, 2003); software used to prepare material for publication: X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Figures top

	Fig. 1. The molecular structure of the title compound showing the atom numbering scheme and the displacement ellipsoids drawn at the 50% probability level. The disorder of the furan moiety is shown different colours, major (blue) and minor (green).
	Fig. 2. The diagram shows the C—H···O hydrogen bond chains which propagate parallel to the b axis.

1-tert-Butyl 2-ethyl 5-chloro-3-(2-furoyl)-1H-indole-1,2-dicarboxylate top

Crystal data top

C₂₁H₂₀ClNO₆	F(000) = 872
M_r = 417.83	D_x = 1.389 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 378(2) K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 9.8354 (8) Å	Cell parameters from 5304 reflections
b = 8.0938 (7) Å	θ = 2.4–27.9°
c = 25.435 (2) Å	µ = 0.23 mm⁻¹
β = 99.344 (1)°	T = 100 K
V = 1997.9 (3) Å³	Square block, colourless
Z = 4	0.32 × 0.32 × 0.24 mm

Data collection top

Bruker APEXII CCD diffractometer	4483 independent reflections
Radiation source: fine-focus sealed tube, Bruker SMART Apex	3877 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
ϕ and ω scans	θ_max = 28.2°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −12→13
T_min = 0.930, T_max = 0.947	k = −10→4
11690 measured reflections	l = −31→33

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.084	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0359P)² + 0.8831P] where P = (F_o² + 2F_c²)/3
4483 reflections	(Δ/σ)_max = 0.001
279 parameters	Δρ_max = 0.29 e Å⁻³
8 restraints	Δρ_min = −0.38 e Å⁻³

Crystal data top

C₂₁H₂₀ClNO₆	V = 1997.9 (3) Å³
M_r = 417.83	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 9.8354 (8) Å	µ = 0.23 mm⁻¹
b = 8.0938 (7) Å	T = 100 K
c = 25.435 (2) Å	0.32 × 0.32 × 0.24 mm
β = 99.344 (1)°

Data collection top

Bruker APEXII CCD diffractometer	4483 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	3877 reflections with I > 2σ(I)
T_min = 0.930, T_max = 0.947	R_int = 0.019
11690 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	8 restraints
wR(F²) = 0.084	H-atom parameters constrained
S = 1.05	Δρ_max = 0.29 e Å⁻³
4483 reflections	Δρ_min = −0.38 e Å⁻³
279 parameters

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.

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Cl1	0.77842 (4)	0.54454 (4)	−0.051345 (13)	0.02592 (10)
O1	0.25661 (9)	0.04213 (12)	0.01491 (4)	0.0207 (2)
N1	0.45710 (11)	0.11938 (13)	0.06875 (4)	0.0152 (2)
C1	0.53993 (13)	0.12814 (16)	0.11858 (5)	0.0157 (3)
O2	0.27094 (9)	0.06519 (12)	0.10504 (3)	0.0189 (2)
C2	0.51962 (13)	0.21382 (16)	0.03288 (5)	0.0157 (2)
O3	0.50752 (10)	−0.12594 (12)	0.16190 (4)	0.0223 (2)
C3	0.47829 (14)	0.24137 (16)	−0.02143 (5)	0.0190 (3)
H3	0.3964	0.1936	−0.0403	0.023*
O4	0.51187 (10)	0.11461 (12)	0.20738 (3)	0.0206 (2)
C4	0.56192 (13)	0.34160 (16)	−0.04673 (5)	0.0214 (3)
H4	0.5379	0.3624	−0.0838	0.026*
O5	0.81234 (10)	0.13738 (12)	0.18938 (4)	0.0221 (2)
C5	0.68105 (13)	0.41230 (16)	−0.01829 (5)	0.0198 (3)
C6	0.72402 (13)	0.38397 (15)	0.03549 (5)	0.0178 (3)
H6	0.8068	0.4308	0.0540	0.021*
C7	0.64034 (12)	0.28344 (15)	0.06143 (5)	0.0160 (3)
C8	0.65137 (13)	0.22643 (16)	0.11585 (5)	0.0158 (2)
C9	0.76525 (12)	0.25249 (16)	0.16090 (5)	0.0167 (3)
C10	0.81371 (13)	0.42143 (17)	0.17023 (5)	0.0177 (3)
C14	0.51626 (12)	0.02212 (16)	0.16433 (5)	0.0161 (3)
C15	0.50330 (16)	0.02643 (19)	0.25714 (5)	0.0262 (3)
H15A	0.4507	−0.0773	0.2490	0.031*
H15B	0.4537	0.0955	0.2800	0.031*
C16	0.64444 (18)	−0.0127 (2)	0.28626 (6)	0.0386 (4)
H16A	0.6977	0.0897	0.2930	0.058*
H16C	0.6911	−0.0873	0.2646	0.058*
H16B	0.6370	−0.0660	0.3203	0.058*
C17	0.31674 (13)	0.06954 (16)	0.05885 (5)	0.0164 (3)
C18	0.12943 (13)	0.00596 (17)	0.10920 (5)	0.0191 (3)
C19	0.02392 (14)	0.12342 (19)	0.07961 (6)	0.0266 (3)
H19A	0.0349	0.1279	0.0420	0.040*
H19B	0.0376	0.2340	0.0953	0.040*
H19C	−0.0690	0.0843	0.0824	0.040*
C20	0.13131 (15)	0.01449 (19)	0.16902 (6)	0.0255 (3)
H20A	0.1547	0.1270	0.1816	0.038*
H20B	0.2002	−0.0629	0.1870	0.038*
H20C	0.0402	−0.0151	0.1770	0.038*
C21	0.11243 (16)	−0.16979 (18)	0.08904 (6)	0.0272 (3)
H21A	0.1883	−0.2376	0.1072	0.041*
H21C	0.1133	−0.1715	0.0506	0.041*
H21B	0.0246	−0.2142	0.0963	0.041*
O6A	0.9318 (4)	0.4474 (3)	0.20578 (19)	0.0224 (4)	0.809 (6)
C11A	0.7582 (4)	0.5688 (4)	0.1527 (3)	0.0194 (6)	0.809 (6)
H11A	0.6773	0.5851	0.1273	0.023*	0.809 (6)
C12A	0.8436 (3)	0.6940 (4)	0.17952 (12)	0.0211 (6)	0.809 (6)
H12A	0.8306	0.8101	0.1763	0.025*	0.809 (6)
C13A	0.9470 (3)	0.6138 (4)	0.21058 (12)	0.0242 (6)	0.809 (6)
H13A	1.0210	0.6668	0.2329	0.029*	0.809 (6)
O6B	0.7353 (13)	0.5546 (12)	0.1514 (8)	0.0194 (6)	0.191 (6)
C11B	0.929 (2)	0.4726 (19)	0.2027 (13)	0.0224 (4)	0.191 (6)
H11B	0.9978	0.4049	0.2228	0.027*	0.191 (6)
C12B	0.9271 (18)	0.6477 (18)	0.2006 (6)	0.0242 (6)	0.191 (6)
H12B	0.9966	0.7204	0.2175	0.029*	0.191 (6)
C13B	0.8072 (14)	0.691 (2)	0.1701 (6)	0.0211 (6)	0.191 (6)
H13B	0.7774	0.8017	0.1628	0.025*	0.191 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0375 (2)	0.01775 (17)	0.02629 (18)	0.00140 (14)	0.01670 (14)	0.00393 (13)
O1	0.0191 (5)	0.0232 (5)	0.0189 (5)	−0.0008 (4)	0.0000 (4)	−0.0042 (4)
N1	0.0155 (5)	0.0154 (5)	0.0146 (5)	0.0006 (4)	0.0022 (4)	−0.0001 (4)
C1	0.0157 (6)	0.0156 (6)	0.0155 (6)	0.0022 (5)	0.0014 (4)	−0.0012 (5)
O2	0.0148 (4)	0.0237 (5)	0.0185 (4)	−0.0018 (4)	0.0034 (3)	−0.0016 (4)
C2	0.0172 (6)	0.0141 (6)	0.0168 (6)	0.0033 (5)	0.0054 (5)	−0.0010 (5)
O3	0.0293 (5)	0.0167 (5)	0.0204 (5)	−0.0011 (4)	0.0027 (4)	0.0004 (4)
C3	0.0210 (6)	0.0181 (6)	0.0174 (6)	0.0047 (5)	0.0019 (5)	−0.0017 (5)
O4	0.0288 (5)	0.0186 (5)	0.0156 (4)	−0.0014 (4)	0.0072 (4)	−0.0002 (4)
C4	0.0305 (7)	0.0195 (7)	0.0150 (6)	0.0076 (6)	0.0061 (5)	0.0008 (5)
O5	0.0212 (5)	0.0219 (5)	0.0219 (5)	0.0017 (4)	−0.0003 (4)	0.0036 (4)
C5	0.0266 (7)	0.0141 (6)	0.0214 (6)	0.0045 (5)	0.0122 (5)	0.0022 (5)
C6	0.0186 (6)	0.0150 (6)	0.0207 (6)	0.0029 (5)	0.0061 (5)	0.0005 (5)
C7	0.0173 (6)	0.0145 (6)	0.0165 (6)	0.0041 (5)	0.0038 (5)	−0.0001 (5)
C8	0.0160 (6)	0.0149 (6)	0.0166 (6)	0.0016 (5)	0.0032 (5)	0.0000 (5)
C9	0.0140 (6)	0.0208 (7)	0.0156 (6)	0.0010 (5)	0.0039 (5)	0.0009 (5)
C10	0.0149 (6)	0.0230 (7)	0.0152 (6)	−0.0019 (5)	0.0021 (5)	0.0004 (5)
C14	0.0130 (6)	0.0186 (6)	0.0165 (6)	0.0001 (5)	0.0013 (4)	−0.0002 (5)
C15	0.0401 (8)	0.0247 (7)	0.0161 (6)	−0.0044 (6)	0.0112 (6)	0.0008 (5)
C16	0.0463 (10)	0.0455 (10)	0.0211 (7)	−0.0115 (8)	−0.0030 (7)	0.0079 (7)
C17	0.0149 (6)	0.0137 (6)	0.0203 (6)	0.0021 (5)	0.0025 (5)	−0.0009 (5)
C18	0.0133 (6)	0.0207 (7)	0.0239 (7)	−0.0016 (5)	0.0051 (5)	−0.0025 (5)
C19	0.0182 (7)	0.0284 (8)	0.0327 (8)	0.0033 (6)	0.0033 (6)	−0.0008 (6)
C20	0.0216 (7)	0.0316 (8)	0.0249 (7)	−0.0040 (6)	0.0091 (5)	−0.0031 (6)
C21	0.0283 (7)	0.0214 (7)	0.0340 (8)	−0.0049 (6)	0.0114 (6)	−0.0045 (6)
O6A	0.0205 (5)	0.0241 (9)	0.0202 (8)	−0.0030 (8)	−0.0043 (4)	0.0034 (10)
C11A	0.0118 (14)	0.0253 (9)	0.0207 (7)	−0.0007 (9)	0.0015 (12)	0.0004 (8)
C12A	0.0194 (16)	0.0205 (7)	0.0230 (14)	−0.0035 (13)	0.0019 (11)	0.0011 (9)
C13A	0.0259 (12)	0.0246 (15)	0.0199 (14)	−0.0089 (10)	−0.0031 (8)	0.0012 (9)
O6B	0.0118 (14)	0.0253 (9)	0.0207 (7)	−0.0007 (9)	0.0015 (12)	0.0004 (8)
C11B	0.0205 (5)	0.0241 (9)	0.0202 (8)	−0.0030 (8)	−0.0043 (4)	0.0034 (10)
C12B	0.0259 (12)	0.0246 (15)	0.0199 (14)	−0.0089 (10)	−0.0031 (8)	0.0012 (9)
C13B	0.0194 (16)	0.0205 (7)	0.0230 (14)	−0.0035 (13)	0.0019 (11)	0.0011 (9)

Geometric parameters (Å, º) top

Cl1—C5	1.7411 (13)	C15—H15A	0.9900
O1—C17	1.1973 (15)	C15—H15B	0.9900
N1—C1	1.3929 (15)	C16—H16A	0.9800
N1—C2	1.4059 (16)	C16—H16C	0.9800
N1—C17	1.4209 (16)	C16—H16B	0.9800
C1—C8	1.3651 (18)	C18—C21	1.5121 (19)
C1—C14	1.4943 (17)	C18—C19	1.5145 (19)
O2—C17	1.3253 (15)	C18—C20	1.5203 (19)
O2—C18	1.4919 (15)	C19—H19A	0.9800
C2—C3	1.3933 (17)	C19—H19B	0.9800
C2—C7	1.4053 (17)	C19—H19C	0.9800
O3—C14	1.2023 (16)	C20—H20A	0.9800
C3—C4	1.3859 (19)	C20—H20B	0.9800
C3—H3	0.9500	C20—H20C	0.9800
O4—C14	1.3329 (15)	C21—H21A	0.9800
O4—C15	1.4672 (16)	C21—H21C	0.9800
C4—C5	1.3959 (14)	C21—H21B	0.9800
C4—H4	0.9500	O6A—C13A	1.359 (3)
O5—C9	1.2240 (16)	C11A—C12A	1.418 (3)
C5—C6	1.3836 (13)	C11A—H11A	0.9500
C6—C7	1.3968 (13)	C12A—C13A	1.349 (3)
C6—H6	0.9500	C12A—H12A	0.9500
C7—C8	1.4463 (16)	C13A—H13A	0.9500
C8—C9	1.4816 (17)	O6B—C13B	1.357 (3)
C9—C10	1.4548 (19)	C11B—C12B	1.418 (4)
C10—C11A	1.357 (3)	C11B—H11B	0.9500
C10—C11B	1.357 (4)	C12B—C13B	1.348 (3)
C10—O6B	1.366 (3)	C12B—H12B	0.9500
C10—O6A	1.367 (2)	C13B—H13B	0.9500
C15—C16	1.497 (2)

C1—N1—C2	108.06 (10)	H16A—C16—H16C	109.5
C1—N1—C17	125.70 (10)	C15—C16—H16B	109.5
C2—N1—C17	123.65 (10)	H16A—C16—H16B	109.5
C8—C1—N1	109.83 (11)	H16C—C16—H16B	109.5
C8—C1—C14	127.02 (11)	O1—C17—O2	129.43 (12)
N1—C1—C14	122.51 (11)	O1—C17—N1	122.44 (12)
C17—O2—C18	121.78 (10)	O2—C17—N1	108.11 (10)
C3—C2—C7	122.29 (12)	O2—C18—C21	109.35 (11)
C3—C2—N1	129.98 (12)	O2—C18—C19	109.57 (11)
C7—C2—N1	107.74 (10)	C21—C18—C19	113.13 (12)
C4—C3—C2	117.04 (12)	O2—C18—C20	101.33 (10)
C4—C3—H3	121.5	C21—C18—C20	111.39 (12)
C2—C3—H3	121.5	C19—C18—C20	111.40 (12)
C14—O4—C15	116.71 (10)	C18—C19—H19A	109.5
C3—C4—C5	120.71 (12)	C18—C19—H19B	109.5
C3—C4—H4	119.6	H19A—C19—H19B	109.5
C5—C4—H4	119.6	C18—C19—H19C	109.5
C6—C5—C4	122.72 (12)	H19A—C19—H19C	109.5
C6—C5—Cl1	118.40 (9)	H19B—C19—H19C	109.5
C4—C5—Cl1	118.87 (9)	C18—C20—H20A	109.5
C5—C6—C7	117.05 (11)	C18—C20—H20B	109.5
C5—C6—H6	121.5	H20A—C20—H20B	109.5
C7—C6—H6	121.5	C18—C20—H20C	109.5
C6—C7—C2	120.18 (11)	H20A—C20—H20C	109.5
C6—C7—C8	132.81 (11)	H20B—C20—H20C	109.5
C2—C7—C8	107.00 (10)	C18—C21—H21A	109.5
C1—C8—C7	107.37 (11)	C18—C21—H21C	109.5
C1—C8—C9	123.78 (11)	H21A—C21—H21C	109.5
C7—C8—C9	128.65 (11)	C18—C21—H21B	109.5
O5—C9—C10	122.45 (11)	H21A—C21—H21B	109.5
O5—C9—C8	121.01 (12)	H21C—C21—H21B	109.5
C10—C9—C8	116.51 (11)	C13A—O6A—C10	106.33 (19)
C11A—C10—C11B	100.6 (7)	C10—C11A—C12A	107.2 (3)
C11B—C10—O6B	110.0 (9)	C10—C11A—H11A	126.4
C11A—C10—O6A	109.6 (2)	C12A—C11A—H11A	126.4
O6B—C10—O6A	118.8 (7)	C13A—C12A—C11A	105.6 (3)
C11A—C10—C9	132.0 (2)	C13A—C12A—H12A	127.2
C11B—C10—C9	127.3 (7)	C11A—C12A—H12A	127.2
O6B—C10—C9	122.2 (6)	C12A—C13A—O6A	111.3 (3)
O6A—C10—C9	118.21 (14)	C12A—C13A—H13A	124.4
O3—C14—O4	126.20 (12)	O6A—C13A—H13A	124.4
O3—C14—C1	123.44 (12)	C13B—O6B—C10	106.7 (13)
O4—C14—C1	110.32 (11)	C10—C11B—C12B	106.0 (11)
O4—C15—C16	110.56 (12)	C10—C11B—H11B	127.0
O4—C15—H15A	109.5	C12B—C11B—H11B	127.0
C16—C15—H15A	109.5	C13B—C12B—C11B	106.8 (15)
O4—C15—H15B	109.5	C13B—C12B—H12B	126.6
C16—C15—H15B	109.5	C11B—C12B—H12B	126.6
H15A—C15—H15B	108.1	C12B—C13B—O6B	110.3 (17)
C15—C16—H16A	109.5	C12B—C13B—H13B	124.9
C15—C16—H16C	109.5	O6B—C13B—H13B	124.9

C2—N1—C1—C8	0.90 (14)	C8—C9—C10—O6A	−170.0 (3)
C17—N1—C1—C8	−161.26 (11)	C15—O4—C14—O3	3.66 (19)
C2—N1—C1—C14	−170.51 (11)	C15—O4—C14—C1	−173.96 (11)
C17—N1—C1—C14	27.33 (19)	C8—C1—C14—O3	−116.54 (15)
C1—N1—C2—C3	178.85 (13)	N1—C1—C14—O3	53.33 (18)
C17—N1—C2—C3	−18.5 (2)	C8—C1—C14—O4	61.16 (17)
C1—N1—C2—C7	−1.16 (13)	N1—C1—C14—O4	−128.97 (12)
C17—N1—C2—C7	161.45 (11)	C14—O4—C15—C16	88.55 (15)
C7—C2—C3—C4	0.00 (19)	C18—O2—C17—O1	6.0 (2)
N1—C2—C3—C4	179.99 (12)	C18—O2—C17—N1	−175.66 (10)
C2—C3—C4—C5	−0.72 (19)	C1—N1—C17—O1	−169.19 (12)
C3—C4—C5—C6	1.7 (2)	C2—N1—C17—O1	31.29 (19)
C3—C4—C5—Cl1	−177.20 (10)	C1—N1—C17—O2	12.35 (17)
C4—C5—C6—C7	−1.74 (19)	C2—N1—C17—O2	−147.17 (11)
Cl1—C5—C6—C7	177.11 (9)	C17—O2—C18—C21	58.82 (15)
C5—C6—C7—C2	0.99 (18)	C17—O2—C18—C19	−65.71 (15)
C5—C6—C7—C8	179.53 (13)	C17—O2—C18—C20	176.51 (11)
C3—C2—C7—C6	−0.15 (19)	C11A—C10—O6A—C13A	0.9 (6)
N1—C2—C7—C6	179.86 (11)	C11B—C10—O6A—C13A	14 (13)
C3—C2—C7—C8	−179.03 (12)	O6B—C10—O6A—C13A	−4.8 (11)
N1—C2—C7—C8	0.98 (13)	C9—C10—O6A—C13A	−174.7 (3)
N1—C1—C8—C7	−0.28 (14)	C11B—C10—C11A—C12A	−3.5 (19)
C14—C1—C8—C7	170.64 (12)	O6B—C10—C11A—C12A	150 (7)
N1—C1—C8—C9	−175.47 (11)	O6A—C10—C11A—C12A	−1.5 (6)
C14—C1—C8—C9	−4.5 (2)	C9—C10—C11A—C12A	173.4 (2)
C6—C7—C8—C1	−179.12 (13)	C10—C11A—C12A—C13A	1.4 (5)
C2—C7—C8—C1	−0.44 (14)	C11A—C12A—C13A—O6A	−0.8 (5)
C6—C7—C8—C9	−4.2 (2)	C10—O6A—C13A—C12A	0.0 (5)
C2—C7—C8—C9	174.43 (12)	C11A—C10—O6B—C13B	−24 (5)
C1—C8—C9—O5	41.90 (19)	C11B—C10—O6B—C13B	3 (3)
C7—C8—C9—O5	−132.21 (14)	O6A—C10—O6B—C13B	6.5 (19)
C1—C8—C9—C10	−136.08 (13)	C9—C10—O6B—C13B	176.0 (10)
C7—C8—C9—C10	49.81 (18)	C11A—C10—C11B—C12B	0 (3)
O5—C9—C10—C11A	−162.5 (4)	O6B—C10—C11B—C12B	−5 (3)
C8—C9—C10—C11A	15.5 (4)	O6A—C10—C11B—C12B	−167 (15)
O5—C9—C10—C11B	14 (2)	C9—C10—C11B—C12B	−176.6 (12)
C8—C9—C10—C11B	−168 (2)	C10—C11B—C12B—C13B	4 (3)
O5—C9—C10—O6B	−157.6 (11)	C11B—C12B—C13B—O6B	−2 (3)
C8—C9—C10—O6B	20.4 (11)	C10—O6B—C13B—C12B	−1 (2)
O5—C9—C10—O6A	12.0 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O1	0.95	2.45	2.9774 (16)	115
C13A—H13A···O5ⁱ	0.95	2.37	3.187 (3)	144
C19—H19A···O1	0.98	2.49	3.0985 (17)	120
C21—H21C···O1	0.98	2.49	3.0615 (17)	117

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

Experimental details

Crystal data
Chemical formula	C₂₁H₂₀ClNO₆
M_r	417.83
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	9.8354 (8), 8.0938 (7), 25.435 (2)
β (°)	99.344 (1)
V (Å³)	1997.9 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.23
Crystal size (mm)	0.32 × 0.32 × 0.24

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.930, 0.947
No. of measured, independent and observed [I > 2σ(I)] reflections	11690, 4483, 3877
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.664

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.084, 1.05
No. of reflections	4483
No. of parameters	279
No. of restraints	8
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.29, −0.38

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C13A—H13A···O5ⁱ	0.95	2.37	3.187 (3)	144

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

Acknowledgements

MH thanks Professor Willem A. L. van Otterlo and Dr S. C. Pelly for their valuable input and research oversight. Stellenbosch University's Science Faculty is also acknowledged for providing laboratory space and financial research support (Subcommittee B). The South African National Research Foundation (NRF), Pretoria, is also acknowledged for providing research funds.

References

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