Crystal structure of (4bS,8aR)-1-isopropyl-4b,8,8-trimethyl-7-oxo-4b,7,8,8a,9,10-hexa-hydro-phenanthren-2-yl acetate.

The title compound, C22H28O3, was prepared by a direct acetyl-ation reaction of naturally occurring totarolenone. The mol-ecule contains three fused rings, which exhibit different conformations. The central ring has a half-chair conformation, while the non-aromatic oxo-substituted ring has a screw-boat conformation. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming sheets parallel to the bc plane. The carbonyl O atoms and the C atom at the 6-position of the cyclo-hexene ring are each disordered over two sets of sites with major occupancy components of 0.63 (7) and 0.793 (14), respectively.

Chemical context

Diterpene phenols are a family of natural products isolated from a variety of terrestrial plant sources. They exhibit a wide variety of inter­esting biological activities such as anti­tumour (Iwamoto et al., 2003 ▸; Son et al. 2005 ▸), anti­microbial (Yoshikawa et al., 2008 ▸; Pereda-Miranda et al., 1992 ▸), anti­viral (Yang et al., 2011 ▸; Wen et al., 2007 ▸) and anti-inflammatory (Chen et al. 2013 ▸). In addition, derivatives of diterpene phenol natural products have been studied extensively as potential chemotherapeutic agents (Areche et al., 2007 ▸; Yang et al. 2001 ▸).

With the aim of preparing diterpene phenol derivatives, we report here the hemisynthesis (Fig. 1 ▸) of (4bS,8aR)-1-isopropyl-4 b,8,8-trimethyl-7-oxo-4 b,7,8,8a,9,10-hexa­hydro­phenanthren-2-yl acetate, 2, from naturally occurring totarolenone, 1, extracted from the heartwood of Tetra­clinis articulata (Chow et al., 1960 ▸). Treatment of 1 with acetic anhydride and pyridine provides compound 2 as colourless crystals in 88% yield. X-ray single crystal structure analysis allowed its structure to be confirmed unambiguously. Its structure was also characterized by 1H and 13C NMR measurements.

Figure 1

Reaction scheme for the synthesis of the title compound 2.

Structural commentary

The mol­ecular structure is built up from three fused six-membered rings (Fig. 2 ▸). In the mol­ecule, there are two chiral carbon atoms, C4b exhibits an S configuration and C8a exhibits an R configuration. The central six-membered ring (C4A, C4B, C8A, C9, C10, C10A) assumes a half-chair conformation, as indicated by the total puckering amplitude Q T = 0.55 (2) Å and spherical polar angle θ = 51.0 (2)° with φ = 136.0 (2)°. The major component of the cyclo­hexene ring exhibits a screw-boat conformation [Q T = 0.462 (2) Å, θ =113.7 (2)°, φ = 145.9 (2)°] while the minor component has a chair conformation [Q T = 0.558 (6) Å, θ =159.4 (6)°, φ = 235.6 (14)°].

Figure 2

The mol­ecular structure of the title compound with the atom-numbering scheme. The displacement ellipsoids are drawn at the 30% probability level. Only the major disorder components are shown.

Supra­molecular features

In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯π inter­actions, forming layers parallel to the bc plane (Table 1 ▸ and Fig. 3 ▸).

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4⋯O1i	0.95	2.50	3.411 (10)	159
C4—H4⋯O1A i	0.95	2.55	3.428 (17)	154
C10—H10B⋯O1A ii	0.99	2.55	3.328 (17)	136
C13—H13C⋯O3iii	0.98	2.59	3.530 (2)	161
C18—H18A⋯Cg1iv	0.98	2.55	3.504 (2)	165

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

Figure 3

A view along the a axis of the crystal packing of the title compound, showing the C—H⋯O hydrogen bonds (orange dashed lines) and C—H⋯π inter­actions (green dashed lines). For clarity, only the H atoms involved in these inter­actions have been included.

Database survey

A search of the Cambridge Structural Database using the 1,2,3,4,4a,9,10,10a-hexa­hydro­phenanthren ring system (Fig. 4 ▸ a) as the main skeleton, revealed the presence of 75 structures. These include several compounds similar to the title compound. One with a similar conformation has a hydroxyl substituent in place of the acetate in the title compound (Benharref et al., 2011 ▸), and three others have a meth­oxy group in position 4b and carbaldehyde/benzene­sulfono­hydrazide (Vo et al., 2008 ▸) or bi­phenyl­sulfonyl (Gu & You, 2011 ▸) in position 9 (Fig. 4 ▸ b), while six entries (Oubabi et al., 2014a ▸,b ▸; Zeroual et al., 2007 ▸, 2008 ▸; Cutfield et al., 1974 ▸; Pettit et al., 2004 ▸) have 1-isopropyl-4b,8,8-trimethyl substit­uents (Fig. 4 ▸ c).

Figure 4

The core structures for database survey: (a) 1,2,3,4,4a,9,10,10a-hexa­hydro­phenanthren, and its (b) 7-oxo with double bond between C5 and C6, (c) 1-isopropyl-4 b,8,8-trimethyl substituents; and (d) the title compound.

Synthesis and crystallization

A solution of totarolenone 1 (300 mg, 1.041 mmol) in acetic anhydride (10 mL) and sodium acetate (290 mg) was heated under reflux for 24 h. After cooling, the solution was extracted with ether (3 × 20 mL). The organic layer was washed with water, dried on anhydrous Na2SO4 and evaporated under reduced pressure. The obtained residue was chromatographed on silica gel column using hexane and ethyl acetate (95/5) as eluent, to give compound 2.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms were placed in calculated positions and refined in the riding model: C—H = 0.95–1.00 Å with U iso(H) = 1.2U eq(C) or 1.5U eq(C-methyl). The carbonyl O atom is disordered over two sites having occupancies of 0.63 (7) and 0.37 (7). Atom C6 atom of the cyclo­hexene ring is disordered over two sites with an occupancy ratio of 0.793 (14):0.207 (14). The absolute structure was reliably determined based on the value of the Flack parameter [0.02 (5)].

Table 2

Experimental details

Crystal data
Chemical formula	C22H28O3
M r	340.44
Crystal system, space group	Monoclinic, P21
Temperature (K)	100
a, b, c (Å)	7.4103 (2), 10.4681 (3), 12.8121 (3)
β (°)	102.235 (1)
V (Å3)	971.28 (4)
Z	2
Radiation type	Cu Kα
μ (mm−1)	0.60
Crystal size (mm)	0.41 × 0.30 × 0.18
Data collection
Diffractometer	D8 Venture CMOS area detector
Absorption correction	Numerical (SADABS; Bruker, 2012 ▸)
No. of measured, independent and observed [I > 2σ(I)] reflections	17946, 3909, 3852
R int	0.029
(sin θ/λ)max (Å−1)	0.625
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.030, 0.077, 1.05
No. of reflections	3909
No. of parameters	252
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.16, −0.17
Absolute structure	Flack x determined using 1757 quotients [(I +)−(I −)]/[(I +)+(I −)] (Parsons et al., 2013 ▸)
Absolute structure parameter	0.02 (5)

Computer programs: APEX2 and SAINT (Bruker, 2012 ▸), SHELXS2014 (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), ORTEP-3 for Windows (Farrugia, 2012 ▸), DIAMOND (Brandenburg et al., 2012 ▸), PLATON (Spek, 2009 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989018005510/xu5922sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989018005510/xu5922Isup2.hkl

CCDC reference: 1835842

Additional supporting information: crystallographic information; 3D view; checkCIF report

C22H28O3	F(000) = 368
Mr = 340.44	Dx = 1.164 Mg m−3
Monoclinic, P21	Cu Kα radiation, λ = 1.54178 Å
a = 7.4103 (2) Å	Cell parameters from 3909 reflections
b = 10.4681 (3) Å	θ = 3.5–74.5°
c = 12.8121 (3) Å	µ = 0.60 mm−1
β = 102.235 (1)°	T = 100 K
V = 971.28 (4) Å3	Block, colourless
Z = 2	0.41 × 0.30 × 0.18 mm

D8 Venture CMOS area detector diffractometer	3852 reflections with I > 2σ(I)
Radiation source: microsource	Rint = 0.029
φ and ω scans	θmax = 74.5°, θmin = 3.5°
Absorption correction: numerical (SADABS; Bruker, 2012)	h = −9→9
	k = −13→13
17946 measured reflections	l = −16→15
3909 independent reflections

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.030	w = 1/[σ2(Fo2) + (0.0376P)2 + 0.2106P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.077	(Δ/σ)max < 0.001
S = 1.05	Δρmax = 0.16 e Å−3
3909 reflections	Δρmin = −0.17 e Å−3
252 parameters	Absolute structure: Flack x determined using 1757 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
1 restraint	Absolute structure parameter: 0.02 (5)

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
O2	0.31864 (16)	−0.17015 (11)	0.35741 (9)	0.0169 (2)
O3	0.57128 (17)	−0.12685 (12)	0.48549 (10)	0.0228 (3)
C1	0.1762 (2)	0.03631 (15)	0.31947 (13)	0.0149 (3)
C2	0.3194 (2)	−0.04717 (15)	0.31317 (12)	0.0141 (3)
C3	0.4591 (2)	−0.01616 (16)	0.26178 (12)	0.0165 (3)
H3	0.5532	−0.0764	0.2575	0.020*
C4	0.4606 (2)	0.10335 (17)	0.21673 (12)	0.0160 (3)
H4	0.5571	0.1253	0.1817	0.019*
C4A	0.3228 (2)	0.19262 (15)	0.22171 (12)	0.0140 (3)
C4B	0.3352 (2)	0.32561 (16)	0.17177 (13)	0.0167 (3)
C5	0.3964 (3)	0.31576 (18)	0.06569 (14)	0.0242 (4)
H5	0.4747	0.2476	0.0544	0.029*
C7	0.2283 (3)	0.5140 (2)	−0.00216 (14)	0.0262 (4)
C8	0.1175 (3)	0.51452 (17)	0.08559 (13)	0.0217 (4)
C8A	0.1410 (2)	0.38675 (17)	0.14900 (12)	0.0166 (3)
H8A	0.0595	0.3243	0.1021	0.020*
C9	0.0693 (2)	0.39088 (17)	0.25247 (13)	0.0195 (3)
H9A	0.1618	0.4325	0.3095	0.023*
H9B	−0.0461	0.4415	0.2413	0.023*
C10	0.0326 (2)	0.25550 (16)	0.28606 (13)	0.0181 (3)
H10A	0.0204	0.2569	0.3615	0.022*
H10B	−0.0866	0.2260	0.2423	0.022*
C10A	0.1817 (2)	0.16011 (16)	0.27480 (12)	0.0143 (3)
C11	−0.0867 (3)	0.5279 (2)	0.02894 (17)	0.0308 (4)
H11A	−0.1038	0.6076	−0.0122	0.046*
H11B	−0.1639	0.5294	0.0823	0.046*
H11C	−0.1223	0.4554	−0.0194	0.046*
C12	0.1723 (4)	0.63433 (19)	0.15482 (19)	0.0409 (6)
H12A	0.1463	0.7108	0.1101	0.061*
H12B	0.3044	0.6310	0.1874	0.061*
H12C	0.1011	0.6374	0.2111	0.061*
C13	0.4868 (3)	0.40095 (19)	0.24898 (16)	0.0252 (4)
H13A	0.5014	0.4854	0.2188	0.038*
H13B	0.6039	0.3543	0.2592	0.038*
H13C	0.4511	0.4109	0.3180	0.038*
C14	0.0212 (2)	−0.00178 (18)	0.37495 (14)	0.0220 (4)
H14	−0.0789	0.0631	0.3538	0.026*
C15	0.0844 (3)	0.0071 (3)	0.49646 (16)	0.0347 (5)
H15A	0.1850	−0.0538	0.5209	0.052*
H15B	−0.0193	−0.0132	0.5300	0.052*
H15C	0.1280	0.0939	0.5163	0.052*
C16	−0.0662 (3)	−0.1325 (2)	0.3410 (2)	0.0352 (5)
H16A	−0.0992	−0.1373	0.2629	0.053*
H16B	−0.1774	−0.1433	0.3701	0.053*
H16C	0.0224	−0.2003	0.3685	0.053*
C17	0.4501 (2)	−0.19878 (16)	0.44565 (13)	0.0165 (3)
C18	0.4186 (3)	−0.32928 (18)	0.48463 (16)	0.0285 (4)
H18A	0.5095	−0.3469	0.5506	0.043*
H18B	0.4316	−0.3924	0.4302	0.043*
H18C	0.2939	−0.3344	0.4988	0.043*
C6	0.3407 (7)	0.4028 (4)	−0.0124 (3)	0.0322 (13)	0.793 (14)
H6	0.3774	0.3905	−0.0784	0.039*	0.793 (14)
C6A	0.4227 (16)	0.4506 (11)	0.0182 (8)	0.014 (3)	0.207 (14)
H6A	0.5335	0.4861	0.0047	0.017*	0.207 (14)
O1	0.222 (3)	0.6074 (7)	−0.0588 (15)	0.040 (3)	0.63 (7)
O1A	0.185 (3)	0.575 (6)	−0.084 (3)	0.059 (7)	0.37 (7)

	U11	U22	U33	U12	U13	U23
O2	0.0188 (5)	0.0125 (5)	0.0173 (5)	−0.0001 (4)	−0.0009 (4)	0.0017 (4)
O3	0.0257 (6)	0.0197 (6)	0.0195 (6)	−0.0038 (5)	−0.0032 (5)	0.0020 (5)
C1	0.0147 (7)	0.0179 (8)	0.0122 (7)	0.0008 (6)	0.0026 (6)	0.0017 (6)
C2	0.0173 (8)	0.0117 (7)	0.0116 (7)	−0.0003 (6)	−0.0006 (6)	0.0008 (6)
C3	0.0167 (7)	0.0189 (8)	0.0139 (7)	0.0058 (6)	0.0028 (6)	−0.0016 (6)
C4	0.0153 (8)	0.0205 (8)	0.0131 (7)	0.0004 (6)	0.0050 (6)	−0.0002 (6)
C4A	0.0182 (8)	0.0139 (7)	0.0095 (7)	0.0002 (6)	0.0022 (6)	0.0000 (6)
C4B	0.0233 (8)	0.0145 (7)	0.0135 (7)	−0.0003 (6)	0.0067 (6)	0.0014 (6)
C5	0.0375 (10)	0.0191 (8)	0.0201 (8)	0.0019 (8)	0.0153 (7)	0.0021 (7)
C7	0.0286 (9)	0.0265 (9)	0.0229 (8)	−0.0030 (8)	0.0040 (7)	0.0099 (8)
C8	0.0302 (9)	0.0153 (8)	0.0193 (8)	0.0023 (7)	0.0043 (7)	0.0048 (7)
C8A	0.0248 (8)	0.0129 (7)	0.0124 (7)	0.0018 (6)	0.0043 (6)	0.0017 (6)
C9	0.0277 (9)	0.0150 (7)	0.0178 (8)	0.0080 (7)	0.0095 (6)	0.0019 (6)
C10	0.0223 (8)	0.0177 (8)	0.0166 (8)	0.0066 (6)	0.0093 (6)	0.0047 (6)
C10A	0.0173 (7)	0.0152 (7)	0.0105 (7)	0.0031 (6)	0.0030 (6)	0.0009 (5)
C11	0.0303 (10)	0.0309 (10)	0.0317 (10)	0.0100 (8)	0.0074 (8)	0.0162 (8)
C12	0.0713 (17)	0.0125 (9)	0.0354 (11)	0.0019 (9)	0.0030 (11)	0.0015 (8)
C13	0.0272 (9)	0.0194 (8)	0.0287 (9)	−0.0055 (7)	0.0053 (7)	0.0001 (7)
C14	0.0174 (8)	0.0239 (9)	0.0272 (9)	0.0060 (7)	0.0103 (7)	0.0119 (7)
C15	0.0367 (11)	0.0482 (12)	0.0249 (9)	0.0116 (10)	0.0192 (8)	0.0138 (9)
C16	0.0174 (8)	0.0298 (11)	0.0587 (13)	−0.0018 (8)	0.0084 (8)	0.0144 (10)
C17	0.0203 (8)	0.0149 (8)	0.0139 (7)	0.0044 (6)	0.0025 (6)	0.0001 (6)
C18	0.0363 (11)	0.0171 (9)	0.0273 (10)	−0.0016 (8)	−0.0037 (8)	0.0071 (7)
C6	0.048 (3)	0.0312 (18)	0.0220 (14)	0.0010 (19)	0.0181 (16)	0.0045 (13)
C6A	0.014 (5)	0.016 (5)	0.014 (4)	−0.010 (4)	0.004 (4)	0.001 (4)
O1	0.042 (5)	0.033 (3)	0.051 (4)	0.010 (2)	0.026 (3)	0.028 (2)
O1A	0.033 (5)	0.095 (17)	0.048 (8)	0.014 (7)	0.012 (5)	0.055 (9)

O2—C17	1.360 (2)	C9—H9A	0.9900
O2—C2	1.4071 (19)	C9—H9B	0.9900
O3—C17	1.200 (2)	C10—C10A	1.519 (2)
C1—C2	1.390 (2)	C10—H10A	0.9900
C1—C10A	1.421 (2)	C10—H10B	0.9900
C1—C14	1.526 (2)	C11—H11A	0.9800
C2—C3	1.378 (2)	C11—H11B	0.9800
C3—C4	1.379 (2)	C11—H11C	0.9800
C3—H3	0.9500	C12—H12A	0.9800
C4—C4A	1.396 (2)	C12—H12B	0.9800
C4—H4	0.9500	C12—H12C	0.9800
C4A—C10A	1.404 (2)	C13—H13A	0.9800
C4A—C4B	1.543 (2)	C13—H13B	0.9800
C4B—C5	1.525 (2)	C13—H13C	0.9800
C4B—C8A	1.545 (2)	C14—C15	1.531 (3)
C4B—C13	1.546 (2)	C14—C16	1.537 (3)
C5—C6	1.352 (3)	C14—H14	1.0000
C5—C6A	1.565 (11)	C15—H15A	0.9800
C5—H5	0.9500	C15—H15B	0.9800
C7—O1	1.213 (10)	C15—H15C	0.9800
C7—O1A	1.215 (16)	C16—H16A	0.9800
C7—C6	1.453 (4)	C16—H16B	0.9800
C7—C8	1.526 (3)	C16—H16C	0.9800
C7—C6A	1.557 (9)	C17—C18	1.490 (2)
C8—C11	1.540 (3)	C18—H18A	0.9800
C8—C12	1.540 (3)	C18—H18B	0.9800
C8—C8A	1.556 (2)	C18—H18C	0.9800
C8A—C9	1.530 (2)	C6—H6	0.9500
C8A—H8A	1.0000	C6A—H6A	0.9500
C9—C10	1.522 (2)
C17—O2—C2	118.24 (12)	C4A—C10A—C1	120.28 (14)
C2—C1—C10A	117.54 (14)	C4A—C10A—C10	121.20 (14)
C2—C1—C14	121.45 (14)	C1—C10A—C10	118.53 (14)
C10A—C1—C14	120.98 (14)	C8—C11—H11A	109.5
C3—C2—C1	122.65 (15)	C8—C11—H11B	109.5
C3—C2—O2	118.38 (14)	H11A—C11—H11B	109.5
C1—C2—O2	118.92 (14)	C8—C11—H11C	109.5
C2—C3—C4	119.16 (15)	H11A—C11—H11C	109.5
C2—C3—H3	120.4	H11B—C11—H11C	109.5
C4—C3—H3	120.4	C8—C12—H12A	109.5
C3—C4—C4A	121.16 (15)	C8—C12—H12B	109.5
C3—C4—H4	119.4	H12A—C12—H12B	109.5
C4A—C4—H4	119.4	C8—C12—H12C	109.5
C4—C4A—C10A	119.13 (14)	H12A—C12—H12C	109.5
C4—C4A—C4B	118.45 (14)	H12B—C12—H12C	109.5
C10A—C4A—C4B	122.38 (14)	C4B—C13—H13A	109.5
C5—C4B—C4A	111.34 (13)	C4B—C13—H13B	109.5
C5—C4B—C8A	107.50 (13)	H13A—C13—H13B	109.5
C4A—C4B—C8A	108.47 (13)	C4B—C13—H13C	109.5
C5—C4B—C13	106.98 (14)	H13A—C13—H13C	109.5
C4A—C4B—C13	107.10 (13)	H13B—C13—H13C	109.5
C8A—C4B—C13	115.50 (14)	C1—C14—C15	111.07 (15)
C6—C5—C4B	120.85 (18)	C1—C14—C16	114.48 (16)
C4B—C5—C6A	111.8 (4)	C15—C14—C16	111.19 (17)
C6—C5—H5	119.6	C1—C14—H14	106.5
C4B—C5—H5	119.6	C15—C14—H14	106.5
O1—C7—C8	118.7 (5)	C16—C14—H14	106.5
O1A—C7—C8	123.5 (13)	C14—C15—H15A	109.5
C6—C7—C8	118.54 (17)	C14—C15—H15B	109.5
C8—C7—C6A	120.1 (3)	H15A—C15—H15B	109.5
C7—C8—C11	106.34 (15)	C14—C15—H15C	109.5
C7—C8—C12	108.06 (17)	H15A—C15—H15C	109.5
C11—C8—C12	108.06 (18)	H15B—C15—H15C	109.5
C7—C8—C8A	111.32 (15)	C14—C16—H16A	109.5
C11—C8—C8A	108.33 (15)	C14—C16—H16B	109.5
C12—C8—C8A	114.38 (14)	H16A—C16—H16B	109.5
C9—C8A—C4B	109.20 (13)	C14—C16—H16C	109.5
C9—C8A—C8	114.04 (14)	H16A—C16—H16C	109.5
C4B—C8A—C8	116.83 (14)	H16B—C16—H16C	109.5
C9—C8A—H8A	105.2	O3—C17—O2	123.70 (15)
C4B—C8A—H8A	105.2	O3—C17—C18	126.10 (15)
C8—C8A—H8A	105.2	O2—C17—C18	110.19 (14)
C10—C9—C8A	109.53 (14)	C17—C18—H18A	109.5
C10—C9—H9A	109.8	C17—C18—H18B	109.5
C8A—C9—H9A	109.8	H18A—C18—H18B	109.5
C10—C9—H9B	109.8	C17—C18—H18C	109.5
C8A—C9—H9B	109.8	H18A—C18—H18C	109.5
H9A—C9—H9B	108.2	H18B—C18—H18C	109.5
C10A—C10—C9	114.07 (14)	C5—C6—C7	124.3 (2)
C10A—C10—H10A	108.7	C5—C6—H6	117.9
C9—C10—H10A	108.7	C7—C6—H6	117.9
C10A—C10—H10B	108.7	C7—C6A—C5	105.2 (7)
C9—C10—H10B	108.7	C7—C6A—H6A	127.4
H10A—C10—H10B	107.6	C5—C6A—H6A	127.4

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O1i	0.95	2.50	3.411 (10)	159
C4—H4···O1Ai	0.95	2.55	3.428 (17)	154
C10—H10B···O1Aii	0.99	2.55	3.328 (17)	136
C13—H13C···O3iii	0.98	2.59	3.530 (2)	161
C18—H18A···Cg1iv	0.98	2.55	3.504 (2)	165