Crystal structure of (–)-methyl (R,E)-4-[(2R,4R)-2-amino-2-tri­chloro­methyl-1,3-dioxolan-4-yl]-4-hy­droxy-2-methyl­but-2-enoate

Oishi, T.; Kidena, M.; Sugai, T.; Sato, T.; Chida, N.

doi:10.1107/S2056989017008283

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ISSN: 2056-9890

Volume 73| Part 7| July 2017| Pages 983-986

https://doi.org/10.1107/S2056989017008283

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Crystal structure of (–)-methyl (R,E)-4-[(2R,4R)-2-amino-2-trichloromethyl-1,3-dioxolan-4-yl]-4-hydroxy-2-methylbut-2-enoate

Takeshi Oishi,^a ^* Mayu Kidena,^b Tomoya Sugai,^b Takaaki Sato ^b and Noritaka Chida ^b

^aSchool of Medicine, Keio University, Hiyoshi 4-1-1, Kohoku-ku, Yokohama 223-8521, Japan, and ^bDepartment of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan
^*Correspondence e-mail: oec@keio.jp

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 1 June 2017; accepted 5 June 2017; online 7 June 2017)

In the title compound, C₁₀H₁₄Cl₃NO₅, the five-membered dioxolane ring adopts an envelope conformation with the C atom bonded to the butenoate side chain as the flap. It deviates from the mean plane of the other atoms in the ring by 0.446 (6) Å. In the crystal, molecules are connected by O—H⋯O hydrogen bonds into helical chains running along the b-axis direction. The chains are linked into a sheet structure parallel to (001) by an N—H⋯O hydrogen bond. These classical hydrogen bonds enclose an R⁴₄(24) graph-set motif in the sheet structure. Furthermore, a weak intermolecular C—H⋯Cl interaction expands the sheet structures into a three-dimensional network.

Keywords: crystal structure; 1,3-dioxolane; hydroxy group; amino group; hydrogen bonding.

CCDC reference: 1554119

1. Chemical context

Cyclic compounds often play a significant role, not only in controlling stereochemistry due to their conformational rigidity, but also as protecting groups in organic synthesis. On the basis of this concept, we have explored the utilization of cyclic orthoamides, prepared from allylic diol and triol with known conditions (Overman, 1974 ; 1976 ), and have developed a new strategy for the total synthesis of a certain natural product (Nakayama, et al., 2013 ). The title compound is a structural isomer of a recently reported compound (Oishi et al., 2016 ).

2. Structural commentary

The molecular structure of the title compound is shown in Fig. 1. The 1,3-dioxolane ring (C5/O7/C8/C9/O10) adopts an envelope conformation with the flap atom C9 deviating by 0.446 (6) Å from the mean plane of the other four atoms [puckering parameters are Q(2) = 0.285 (4) Å and φ(2) = 296.7 (8)°]. The C=C and C=O double bonds of the unsaturated ester are slightly skewed with torsion angle C13=C14—C16=O18 being of 8.4 (6)°. There is a weak intramolecular N6—H6A⋯Cl1 interaction present (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N6—H6A⋯Cl1	0.87 (2)	2.66 (4)	3.118 (4)	115 (3)
O12—H12⋯O17ⁱ	0.84	1.97	2.774 (4)	161
N6—H6B⋯O12ⁱⁱ	0.84 (2)	2.28 (3)	3.047 (5)	152 (4)
C8—H8B⋯Cl2ⁱⁱⁱ	0.99	2.83	3.713 (5)	149
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z]$ ; (ii) x-1, y, z; (iii) $[-x+1, y+{\script{1\over 2}}, -z+1]$ .

Figure 1
The molecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. The purple dotted line indicates the short intramolecular N—H⋯Cl contact (see Table 1

). Only H atoms connected to N, O and chiral C atoms are shown for clarity.

3. Supramolecular features

In the crystal, a classical O—H⋯O hydrogen bond (O12—H12⋯O17ⁱ; Table 1) connects the molecules into a helical-chain running along the b-axis direction, with a C(7) graph-set motif (Fig. 2). A classical N—H⋯O hydrogen bond (N6—H6B⋯O12ⁱⁱ; Table 1), which is formed between one of N-bound H atoms and hydroxy O group, links the chains into a sheet structure parallel to (001), also generating a C(7) graph-set motif (Fig. 3). In the sheet structure, the classical O—H⋯O and N—H⋯O hydrogen bonds enclose an R₄⁴(24) graph-set motif (Fig. 4). Furthermore, a weak C—H⋯Cl interaction (C8—H8B⋯Cl2ⁱⁱⁱ; Table 1) supports the crystal packing to construct a three-dimensional architecture (Fig. 2). An intermolecular Cl1⋯O17 (x, y − 1, z) short contact of 3.076 (3) Å is also observed.

Figure 2
The crystal packing of the title compound, viewed along the a axis, showing the helical chain structures running along the b-axis direction. Yellow lines indicate the intermolecular O—H⋯O hydrogen bonds. Black dashed lines indicate weak intermolecular C—H⋯Cl interactions. Only H atoms involved in the hydrogen bonds are shown for clarity. [Symmetry codes: (i) −x + 1, y – 1/2, −z; (iii) −x + 1, y + $[{1\over 2}]$ , −z + 1.]

Figure 3
The crystal packing of the title compound, viewed along the c axis, showing the sheet structure parallel to (001). The helical chain running along the b-axis direction is drawn as overlapped molecules. Yellow lines indicate the intermolecular N—H⋯O hydrogen bonds. Only H atoms involved in the hydrogen bonds are shown for clarity. [Symmetry code: (ii) x – 1, y, z.]

Figure 4
A part of sheet structure, showing the R₄⁴ graph-set motif generated by classical O—H⋯O and N—H⋯O hydrogen bonds. Yellow lines indicate the intermolecular O—H⋯O and N—H⋯O hydrogen bonds. Only H atoms involved in the hydrogen bonds are shown for clarity. [Symmetry codes: (i) −x + 1, y – 1/2, −z; (ii) x – 1, y, z; (iv) −x, y − $[{1\over 2}]$ , −z.]

4. Database survey

In the Cambridge Structural Database (CSD, Version 5.38, Feb. 2017; Groom et al., 2016 ), there are two structures containing the 4-alkoxy-2-methyl-4-(2-methyl-1,3-dioxolan-4-yl)but-2-enoate skeleton, (a), related to the title compound (Fig. 5), but its 4-hydroxy free derivative (R = H) has not yet been reported.

Figure 5
The core structures for the database survey; (a) 4-alkoxy-2-methyl-4-(2-methyl-1,3-dioxolan-4-yl)but-2-enoate, (b) 2-amino-2-trichloromethyl-1,3-dioxolane, and its (c) -1,3-oxathiolane and (d) -1,3-dioxane derivatives instead of the 1,3-dioxolane ring.

For the cyclic orthoamide core with a trichloromethyl group on the central carbon atom, four structures are registered in the CSD. These are two derivatives (WEKWOY: Haeckel et al., 1994 ; and LAGMAK: Oishi et al., 2016) of 1,3-dioxolane (b), one derivative (WAXBEE: Metwally, 2011 ) of 1,3-oxathiolane (c), and one derivative (LIBHIO: Rondot et al., 2007 ) of 1,3-dioxane (d). The amino H atoms were refined as adopting an sp² configuration for WEKWOY and WAXBEE, while they were refined assuming an sp³ configuration of the N atom for LIBHIO and LAGMAK, as in the present study. Each N—H bond of the amino group in LIBHIO is mostly eclipsed by the neighbouring C—Cl bonds of the trichloromethyl group, whereas those in the title compound are slightly tilted (Fig. 6). There is an intramolecular N—H⋯Cl interaction [H6A⋯Cl1 = 2.66 (4) Å; N6—H6A⋯Cl1 = 115 (3)°] in the title compound (Table 1), while the corresponding geometries are 2.76 Å and 109° in LIBHIO. These amino groups may be oriented to avoid intramolecular non-bonding short contacts as well as to form classical intermolecular hydrogen bonds. The amino H atoms in LAGMAK are disordered according to the possible intramolecular N—H⋯O and N⋯H—O hydrogen bonds with the hydroxy group (Oishi et al., 2016).

Figure 6
A projected diagram looking through the N atom of the amino group onto the C atom of the trichloromethyl group.

5. Synthesis and crystallization

The title compound was afforded from L-threose, which can be prepared according to the reported procedure (Smith et al., 1992 ) from D-galactose (Kidena et al., 2017 ). Purification was carried out by silica gel column chromatography, and colourless crystals were obtained from a benzene solution under a hexane-saturated atmosphere, by slow evaporation at ambient temperature (m.p. 358–359 K). [α]_D²⁴ – 32.7 (c 1.01, CHCl₃). HRMS (ESI) m/z calculated for C₁₀H₁₅Cl₃NO₅⁺ [M + H]⁺: 334.0016; found: 334.0016.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. C-bound H atoms were positioned geometrically with C—H = 0.95–1.00 Å, and constrained to ride on their parent atoms with U_iso(H) = 1.5U_eq(methyl C) and 1.2U_eq(C) for other C-bound H atoms. The hydroxy H atom was placed, guided by difference-Fourier maps, with O—H = 0.84 Å and refined with U_iso(H) = 1.5U_eq(O). The amino H atoms were placed, guided by difference-Fourier maps, and were refined with distance restraints of N—H = 0.86 (2) Å and H⋯H = 1.40 (2) Å, with U_iso(H) = 1.2U_eq(N).

Table 2
Experimental details

Crystal data
Chemical formula	C₁₀H₁₄Cl₃NO₅
M_r	334.57
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	90
a, b, c (Å)	5.8494 (4), 12.6458 (8), 9.5658 (6)
β (°)	104.763 (2)
V (Å³)	684.23 (8)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.68
Crystal size (mm)	0.28 × 0.22 × 0.08

Data collection
Diffractometer	Bruker D8 Venture
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.83, 0.95
No. of measured, independent and observed [I > 2σ(I)] reflections	10686, 2376, 2268
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.060, 1.06
No. of reflections	2376
No. of parameters	181
No. of restraints	4
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.29
Absolute structure	Flack x determined using 993 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 ).
Absolute structure parameter	0.04 (3)
Computer programs: APEX3 and SAINT (Bruker, 2016), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2014/7 (Sheldrick, 2015b ), Mercury (Macrae et al., 2008 ), publCIF (Westrip, 2010 ) and PLATON (Spek, 2009 ).

Supporting information

CCDC reference: 1554119

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2056989017008283/su5377sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017008283/su5377Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989017008283/su5377Isup3.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010) and PLATON (Spek, 2009).

(-)-Methyl (R,E)-4-[(2R,4R)-2-amino-2-trichloromethyl-1,3-dioxolan-4-yl]-4-hydroxy-2-methylbut-2-enoate top

Crystal data top

C₁₀H₁₄Cl₃NO₅	D_x = 1.624 Mg m⁻³
M_r = 334.57	Melting point = 358–359 K
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
a = 5.8494 (4) Å	Cell parameters from 8568 reflections
b = 12.6458 (8) Å	θ = 2.7–25.4°
c = 9.5658 (6) Å	µ = 0.68 mm⁻¹
β = 104.763 (2)°	T = 90 K
V = 684.23 (8) Å³	Plate, colorless
Z = 2	0.28 × 0.22 × 0.08 mm
F(000) = 344

Data collection top

Bruker D8 Venture diffractometer	2376 independent reflections
Radiation source: fine-focus sealed tube	2268 reflections with I > 2σ(I)
Multilayered confocal mirror monochromator	R_int = 0.042
Detector resolution: 7.4074 pixels mm^-1	θ_max = 25.0°, θ_min = 2.2°
φ and ω scans	h = −6→6
Absorption correction: multi-scan (SADABS; Bruker, 2016)	k = −15→15
T_min = 0.83, T_max = 0.95	l = −11→11
10686 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.030	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.060	w = 1/[σ²(F_o²) + 0.7994P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
2376 reflections	Δρ_max = 0.28 e Å⁻³
181 parameters	Δρ_min = −0.29 e Å⁻³
4 restraints	Absolute structure: Flack x determined using 993 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013).
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (3)

Special details top

Experimental. IR (film): 3393, 3325, 2953, 1714, 1438, 1239, 1093, 1035, 825, 803, 749 cm^-1; ¹H NMR (500 MHz, CDCl₃): δ (p.p.m.) 6.78 (dq, J = 8.7, 1.4 Hz, 1H; H13), 4.69–4.62 (m, 1H; H12), 4.65 (ddd, J = 7.0, 4.3, 2.9 Hz, 1H; H9), 4.43–4.39 (m, 3H; H8AB & H11), 3.75 (s, 3H; H19ABC), 2.95 (bs, 2H; H6AB), 1.92 (d, J = 1.4 Hz, 3H; H14ABC); ¹³C NMR (125 MHz, CDCl₃): δ (p.p.m.) 168.2 (C; C16), 138.9 (CH; C13), 130.2 (C; C14), 116.0 (C; C5), 103.3 (C; C4), 82.9 (CH; C9), 70.1 (CH₂; C8), 69.2 (CH; C11), 52.2 (CH₃; C19), 13.2 (CH₃; C14).

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 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
Cl1	0.49362 (19)	0.09132 (8)	0.28126 (12)	0.0182 (2)
Cl2	0.63815 (19)	0.22438 (8)	0.53302 (11)	0.0188 (3)
Cl3	0.14274 (19)	0.19083 (8)	0.40183 (12)	0.0218 (3)
C4	0.4229 (7)	0.2071 (3)	0.3659 (4)	0.0158 (9)
C5	0.4173 (7)	0.3050 (3)	0.2656 (5)	0.0136 (9)
N6	0.2535 (7)	0.2954 (3)	0.1287 (4)	0.0173 (8)
H6A	0.236 (7)	0.230 (2)	0.099 (5)	0.021*
H6B	0.121 (6)	0.321 (3)	0.128 (5)	0.021*
O7	0.3602 (5)	0.3953 (2)	0.3345 (3)	0.0151 (7)
C8	0.5670 (8)	0.4608 (3)	0.3782 (5)	0.0163 (10)
H8A	0.6482	0.4492	0.4812	0.02*
H8B	0.5255	0.5366	0.3633	0.02*
C9	0.7202 (8)	0.4255 (3)	0.2809 (4)	0.0149 (9)
H9	0.8909	0.4302	0.334	0.018*
O10	0.6524 (5)	0.3163 (2)	0.2537 (3)	0.0136 (6)
C11	0.6763 (8)	0.4863 (3)	0.1386 (5)	0.0146 (10)
H11	0.508	0.4774	0.0826	0.018*
O12	0.8311 (5)	0.4449 (2)	0.0574 (3)	0.0162 (7)
H12	0.7506	0.417	−0.019	0.024*
C13	0.7305 (7)	0.6008 (3)	0.1666 (4)	0.0142 (9)
H13	0.8909	0.6187	0.2091	0.017*
C14	0.5772 (7)	0.6801 (4)	0.1381 (4)	0.0137 (9)
C15	0.3168 (7)	0.6713 (4)	0.0683 (5)	0.0198 (10)
H15A	0.282	0.7022	−0.0288	0.03*
H15B	0.2282	0.7093	0.1268	0.03*
H15C	0.2704	0.5966	0.0615	0.03*
C16	0.6582 (8)	0.7912 (3)	0.1764 (5)	0.0146 (10)
O17	0.5238 (5)	0.8654 (2)	0.1682 (3)	0.0165 (7)
O18	0.8922 (5)	0.8021 (2)	0.2209 (3)	0.0151 (7)
C19	0.9749 (8)	0.9094 (3)	0.2504 (5)	0.0209 (11)
H19A	1.1481	0.9103	0.2763	0.031*
H19B	0.918	0.9378	0.3307	0.031*
H19C	0.9147	0.953	0.1641	0.031*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0221 (6)	0.0107 (5)	0.0232 (6)	0.0009 (5)	0.0080 (5)	−0.0014 (5)
Cl2	0.0220 (6)	0.0165 (6)	0.0159 (5)	−0.0020 (5)	0.0014 (4)	0.0028 (5)
Cl3	0.0160 (6)	0.0218 (6)	0.0312 (6)	−0.0003 (5)	0.0124 (5)	0.0039 (5)
C4	0.015 (2)	0.017 (3)	0.017 (2)	−0.0005 (19)	0.0063 (18)	−0.001 (2)
C5	0.012 (2)	0.012 (2)	0.016 (2)	−0.0005 (19)	0.0046 (19)	−0.0001 (19)
N6	0.0160 (19)	0.017 (2)	0.018 (2)	0.0019 (17)	0.0027 (17)	−0.0012 (17)
O7	0.0155 (16)	0.0100 (16)	0.0208 (16)	0.0031 (13)	0.0068 (13)	−0.0037 (13)
C8	0.022 (2)	0.011 (2)	0.016 (2)	−0.002 (2)	0.0044 (19)	−0.0007 (19)
C9	0.016 (2)	0.012 (2)	0.016 (2)	−0.0047 (18)	0.0028 (18)	−0.0050 (19)
O10	0.0141 (15)	0.0077 (15)	0.0204 (16)	0.0000 (12)	0.0068 (13)	0.0006 (12)
C11	0.014 (2)	0.013 (2)	0.016 (2)	0.0026 (18)	0.0025 (19)	0.0009 (19)
O12	0.0160 (16)	0.0174 (17)	0.0154 (16)	−0.0006 (13)	0.0042 (13)	−0.0033 (14)
C13	0.014 (2)	0.014 (2)	0.015 (2)	−0.0002 (19)	0.0040 (18)	−0.002 (2)
C14	0.018 (2)	0.011 (2)	0.013 (2)	−0.003 (2)	0.0053 (18)	0.0030 (19)
C15	0.014 (2)	0.016 (2)	0.030 (3)	0.0027 (19)	0.006 (2)	0.000 (2)
C16	0.018 (2)	0.017 (2)	0.010 (2)	0.001 (2)	0.0072 (18)	0.002 (2)
O17	0.0167 (16)	0.0138 (16)	0.0186 (16)	0.0034 (14)	0.0034 (13)	0.0005 (14)
O18	0.0124 (16)	0.0105 (15)	0.0208 (16)	−0.0026 (13)	0.0016 (13)	−0.0004 (13)
C19	0.020 (3)	0.009 (2)	0.030 (3)	−0.0012 (19)	0.000 (2)	−0.003 (2)

Geometric parameters (Å, º) top

Cl1—C4	1.773 (4)	C11—C13	1.492 (6)
Cl2—C4	1.778 (4)	C11—H11	1.0
Cl3—C4	1.770 (4)	O12—H12	0.84
C4—C5	1.561 (6)	C13—C14	1.327 (6)
C5—O7	1.401 (5)	C13—H13	0.95
C5—O10	1.416 (5)	C14—C16	1.498 (6)
C5—N6	1.417 (6)	C14—C15	1.503 (6)
N6—H6A	0.87 (2)	C15—H15A	0.98
N6—H6B	0.84 (2)	C15—H15B	0.98
O7—C8	1.438 (5)	C15—H15C	0.98
C8—C9	1.514 (6)	C16—O17	1.213 (5)
C8—H8A	0.99	C16—O18	1.333 (5)
C8—H8B	0.99	O18—C19	1.444 (5)
C9—O10	1.442 (5)	C19—H19A	0.98
C9—C11	1.527 (6)	C19—H19B	0.98
C9—H9	1.0	C19—H19C	0.98
C11—O12	1.433 (5)

C5—C4—Cl3	109.6 (3)	O12—C11—C13	108.4 (3)
C5—C4—Cl1	110.2 (3)	O12—C11—C9	108.3 (3)
Cl3—C4—Cl1	109.1 (2)	C13—C11—C9	110.4 (3)
C5—C4—Cl2	110.8 (3)	O12—C11—H11	109.9
Cl3—C4—Cl2	108.6 (2)	C13—C11—H11	109.9
Cl1—C4—Cl2	108.5 (2)	C9—C11—H11	109.9
O7—C5—O10	108.0 (3)	C11—O12—H12	109.5
O7—C5—N6	108.5 (3)	C14—C13—C11	126.5 (4)
O10—C5—N6	112.1 (3)	C14—C13—H13	116.7
O7—C5—C4	109.1 (3)	C11—C13—H13	116.7
O10—C5—C4	105.1 (3)	C13—C14—C16	120.2 (4)
N6—C5—C4	113.8 (4)	C13—C14—C15	126.2 (4)
C5—N6—H6A	112 (3)	C16—C14—C15	113.6 (4)
C5—N6—H6B	112 (3)	C14—C15—H15A	109.5
H6A—N6—H6B	109 (4)	C14—C15—H15B	109.5
C5—O7—C8	108.8 (3)	H15A—C15—H15B	109.5
O7—C8—C9	103.7 (3)	C14—C15—H15C	109.5
O7—C8—H8A	111.0	H15A—C15—H15C	109.5
C9—C8—H8A	111.0	H15B—C15—H15C	109.5
O7—C8—H8B	111.0	O17—C16—O18	122.5 (4)
C9—C8—H8B	111.0	O17—C16—C14	123.3 (4)
H8A—C8—H8B	109.0	O18—C16—C14	114.2 (4)
O10—C9—C8	102.4 (3)	C16—O18—C19	115.2 (3)
O10—C9—C11	110.2 (3)	O18—C19—H19A	109.5
C8—C9—C11	114.1 (4)	O18—C19—H19B	109.5
O10—C9—H9	110.0	H19A—C19—H19B	109.5
C8—C9—H9	110.0	O18—C19—H19C	109.5
C11—C9—H9	110.0	H19A—C19—H19C	109.5
C5—O10—C9	108.0 (3)	H19B—C19—H19C	109.5

Cl3—C4—C5—O7	59.6 (4)	C4—C5—O10—C9	−131.3 (3)
Cl1—C4—C5—O7	179.7 (3)	C8—C9—O10—C5	27.3 (4)
Cl2—C4—C5—O7	−60.2 (4)	C11—C9—O10—C5	−94.5 (4)
Cl3—C4—C5—O10	175.2 (3)	O10—C9—C11—O12	−65.3 (4)
Cl1—C4—C5—O10	−64.7 (3)	C8—C9—C11—O12	−179.8 (3)
Cl2—C4—C5—O10	55.5 (4)	O10—C9—C11—C13	176.1 (3)
Cl3—C4—C5—N6	−61.8 (4)	C8—C9—C11—C13	61.6 (5)
Cl1—C4—C5—N6	58.4 (4)	O12—C11—C13—C14	127.4 (4)
Cl2—C4—C5—N6	178.5 (3)	C9—C11—C13—C14	−114.1 (5)
O10—C5—O7—C8	−4.9 (4)	C11—C13—C14—C16	178.3 (4)
N6—C5—O7—C8	−126.7 (4)	C11—C13—C14—C15	−1.5 (7)
C4—C5—O7—C8	108.8 (3)	C13—C14—C16—O17	−171.5 (4)
C5—O7—C8—C9	21.5 (4)	C15—C14—C16—O17	8.3 (6)
O7—C8—C9—O10	−29.3 (4)	C13—C14—C16—O18	8.4 (6)
O7—C8—C9—C11	89.7 (4)	C15—C14—C16—O18	−171.7 (3)
O7—C5—O10—C9	−14.9 (4)	O17—C16—O18—C19	−3.5 (6)
N6—C5—O10—C9	104.6 (4)	C14—C16—O18—C19	176.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N6—H6A···Cl1	0.87 (2)	2.66 (4)	3.118 (4)	115 (3)
O12—H12···O17ⁱ	0.84	1.97	2.774 (4)	161
N6—H6B···O12ⁱⁱ	0.84 (2)	2.28 (3)	3.047 (5)	152 (4)
C8—H8B···Cl2ⁱⁱⁱ	0.99	2.83	3.713 (5)	149

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

Acknowledgements

We thank Professor S. Ohba (Keio University, Japan) for his valuable advice.

Funding information

Funding for this research was provided by: Keio Gijuku Fukuzawa Memorial Fund for the Advancement of Education and Research.

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