12-Ethyl-6a,10a-di­hydro-5H-6-oxachrysene

Lough, A.J.; Pounder, A.; Tam, W.

doi:10.1107/S2414314620002862

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 5| Part 3| March 2020| x200286

https://doi.org/10.1107/S2414314620002862

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access

12-Ethyl-6a,10a-dihydro-5H-6-oxachrysene

Alan J. Lough,^a ^* Austin Pounder ^b and William Tam ^b

^aDepartment of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada, and ^bDepartment of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
^*Correspondence e-mail: alan.lough@utoronto.ca

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 26 February 2020; accepted 1 March 2020; online 5 March 2020)

In the title compound, C₁₉H₁₆O, the pyran ring is in a half-chair conformation. The essentially planar naphthalene ring system (r.m.s. deviation = 0.020 Å) forms a dihedral angle of 14.37 (5)° with the fused benzene ring. In the crystal, pairs of molecules are connected into inversion dimers by weak C—H⋯O hydrogen bonds to generate R₂²(6) loops.

Keywords: crystal structure; regioisomer; fused-rings; weak hydrogen bonds.

CCDC reference: 1987308

Structure description

In past years, our research group has investigated the effects of various C₁-substituted oxabenzonorbornadienes (OBD) on controlling the regioselectivity of ring-opening reactions (Hill et al., 2019 ; Hill & Tam, 2019 ; Edmunds et al., 2015 ; Raheem et al., 2014 ; Boutin et al., 2019 ). To date, there have been very limited investigations into the C₁-tethered intramolecular ring-opening reactions of OBD and derivatives thereof (Loh et al., 2016 ; Wicks et al., 2019 ). Recently, our group looked into the palladium-catalysed intramolecular arylation of oxabenzonorbornadiene derivatives. Reaction of the C₁-tethered unsymmetrical OBD I (see Fig. 3) in the presence of Pd(PPh₃)₂Cl₂, Zn powder, and Et₃N in acetonitrile afforded the dehydrated II and hydrated III ring-opened products in an 87% and 3% yield respectively. Of the two potential regioisomers, the reaction was found to give solely the C₂-cyclized regioisomer.

Figure 3
The reaction scheme.

The molecular structure of the title compound is shown in Fig. 1. The pyran ring (C1—C4/O1/C9) is in a half-chair conformation with atoms O1 and C1 displaced from the mean plane of the other four atoms by −0.260 (1) and 0.330 (1) Å, respectively. The essentially planar naphthalene ring system (C2/C3/C10–C17) forms a dihedral angle of 14.37 (5)° with the fused benzene ring (C4–C9). In the crystal, pairs of molecules are connected into inversion dimers (Fig. 2) by weak C—H⋯O hydrogen bonds (Table 1) to generate $[R_{2}^{2}]$ (6) loops.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1A⋯O1ⁱ	0.99	2.49	3.3514 (14)	146
Symmetry code: (i) -x, -y+1, -z+1.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.

Figure 2
Part of the crystal structure with weak hydrogen bonds shown as dashed lines.

Synthesis and crystallization

To a 2 dram vial was added the aryl iodide-tethered oxabenzonorbornadiene I (73.0 mg, 0.180 mmol) (see Fig. 3). The vial was purged with argon for 5 minutes before being imported into an inert glove box. Inside the glove box, Pd(PPh₃)₂Cl₂ (10.8 mg, 15.3 µmol, 8 mol%) and Zn powder (41.3 mg, 0.631 mmol) were added to the vial and dissolved in 1 ml of MeCN, followed by subsequent addition of Et₃N (0.12 ml, 8 mol%). The vial was exported and stirred at 333 K for 20 h. The crude solution was purified by flash chromatography (EtOAc:hexanes, 15: 85) by loading directly onto the column to obtained ring-opened products II (23.5 mg, 0.0904 mmol, 87%) and III (1.5 mg, 5.34 µmol, 3%) as white solids. These were subsequently crystallized from DCM solution by slow evaporation of the solvent to afford product II as colourless crystals.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₉H₁₆O
M_r	260.32
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	150
a, b, c (Å)	9.4802 (3), 14.9824 (7), 18.6565 (7)
V (Å³)	2649.90 (18)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	0.08
Crystal size (mm)	0.34 × 0.28 × 0.20

Data collection
Diffractometer	Bruker Kappa APEX DUO CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.712, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	12018, 3052, 2504
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.651

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.101, 1.04
No. of reflections	3052
No. of parameters	182
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.20
Computer programs: APEX3 and SAINT (Bruker, 2018 ), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ), PLATON (Spek, 2020 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1987308

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314620002862/hb4339sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620002862/hb4339Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314620002862/hb4339Isup3.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2018); cell refinement: APEX3 (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: PLATON (Spek, 2020); software used to prepare material for publication: publCIF (Westrip, 2010).

12-Ethyl-6a,10a-dihydro-5H-6-oxachrysene top

Crystal data top

C₁₉H₁₆O	D_x = 1.305 Mg m⁻³
M_r = 260.32	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 4405 reflections
a = 9.4802 (3) Å	θ = 2.7–27.5°
b = 14.9824 (7) Å	µ = 0.08 mm⁻¹
c = 18.6565 (7) Å	T = 150 K
V = 2649.90 (18) Å³	Block, colourless
Z = 8	0.34 × 0.28 × 0.20 mm
F(000) = 1104

Data collection top

Bruker Kappa APEX DUO CCD diffractometer	2504 reflections with I > 2σ(I)
Radiation source: sealed tube with Bruker Triumph monochromator	R_int = 0.024
φ and ω scans	θ_max = 27.6°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −12→7
T_min = 0.712, T_max = 0.746	k = −14→19
12018 measured reflections	l = −23→17
3052 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.101	w = 1/[σ²(F_o²) + (0.045P)² + 0.903P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3052 reflections	Δρ_max = 0.22 e Å⁻³
182 parameters	Δρ_min = −0.20 e Å⁻³
0 restraints

Special details top

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.

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

	x	y	z	U_iso*/U_eq
O1	0.14745 (9)	0.56200 (6)	0.52772 (5)	0.0288 (2)
C1	0.19567 (12)	0.47662 (8)	0.50242 (7)	0.0253 (3)
H1A	0.113259	0.440513	0.487550	0.030*
H1B	0.243243	0.444816	0.542161	0.030*
C2	0.29601 (11)	0.48465 (7)	0.44035 (6)	0.0203 (2)
C3	0.38550 (11)	0.55736 (7)	0.43874 (6)	0.0195 (2)
C4	0.37337 (12)	0.62461 (7)	0.49599 (6)	0.0205 (2)
C5	0.47302 (12)	0.69135 (8)	0.50892 (6)	0.0233 (2)
H5A	0.557021	0.692806	0.481172	0.028*
C6	0.45198 (13)	0.75556 (8)	0.56139 (7)	0.0268 (3)
H6A	0.520398	0.800926	0.568953	0.032*
C7	0.33054 (14)	0.75316 (9)	0.60274 (7)	0.0296 (3)
H7A	0.315739	0.797104	0.638675	0.036*
C8	0.23061 (13)	0.68699 (9)	0.59193 (7)	0.0289 (3)
H8A	0.147770	0.685153	0.620547	0.035*
C9	0.25251 (12)	0.62354 (8)	0.53905 (6)	0.0233 (3)
C10	0.30578 (12)	0.41727 (7)	0.38677 (6)	0.0213 (2)
C11	0.21812 (13)	0.34026 (8)	0.38753 (7)	0.0271 (3)
H11A	0.148683	0.334068	0.423906	0.033*
C12	0.23206 (14)	0.27487 (8)	0.33676 (7)	0.0321 (3)
H12A	0.172461	0.223924	0.338117	0.038*
C13	0.33420 (15)	0.28297 (8)	0.28273 (7)	0.0318 (3)
H13A	0.343672	0.237217	0.247801	0.038*
C14	0.42019 (14)	0.35610 (8)	0.27990 (6)	0.0268 (3)
H14A	0.488670	0.360520	0.242901	0.032*
C15	0.40889 (12)	0.42557 (7)	0.33134 (6)	0.0216 (2)
C16	0.49793 (12)	0.50263 (8)	0.32932 (6)	0.0218 (2)
C17	0.48407 (12)	0.56564 (7)	0.38189 (6)	0.0212 (2)
H17A	0.542758	0.616993	0.380285	0.025*
C18	0.60196 (13)	0.51671 (8)	0.26905 (7)	0.0284 (3)
H18A	0.651154	0.459737	0.259180	0.034*
H18B	0.673658	0.560771	0.284435	0.034*
C19	0.53232 (16)	0.54966 (9)	0.20008 (7)	0.0357 (3)
H19A	0.604987	0.561189	0.163888	0.054*
H19B	0.480278	0.604847	0.209855	0.054*
H19C	0.467017	0.504057	0.182266	0.054*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0198 (4)	0.0327 (5)	0.0339 (5)	−0.0022 (3)	0.0041 (4)	−0.0043 (4)
C1	0.0218 (5)	0.0262 (6)	0.0279 (6)	−0.0031 (5)	0.0016 (5)	0.0020 (5)
C2	0.0166 (5)	0.0218 (5)	0.0224 (6)	0.0010 (4)	−0.0030 (4)	0.0044 (4)
C3	0.0172 (5)	0.0201 (5)	0.0213 (5)	0.0022 (4)	−0.0026 (4)	0.0034 (4)
C4	0.0199 (5)	0.0209 (5)	0.0206 (5)	0.0027 (4)	−0.0034 (4)	0.0038 (4)
C5	0.0231 (5)	0.0223 (6)	0.0245 (6)	0.0005 (4)	−0.0022 (5)	0.0043 (5)
C6	0.0307 (6)	0.0223 (6)	0.0273 (6)	0.0001 (5)	−0.0077 (5)	0.0019 (5)
C7	0.0367 (7)	0.0272 (6)	0.0250 (6)	0.0068 (5)	−0.0047 (5)	−0.0033 (5)
C8	0.0270 (6)	0.0341 (7)	0.0255 (6)	0.0051 (5)	0.0018 (5)	−0.0013 (5)
C9	0.0214 (5)	0.0246 (6)	0.0240 (6)	0.0008 (4)	−0.0031 (4)	0.0025 (5)
C10	0.0207 (5)	0.0207 (5)	0.0224 (6)	−0.0001 (4)	−0.0054 (4)	0.0042 (4)
C11	0.0283 (6)	0.0260 (6)	0.0270 (6)	−0.0049 (5)	−0.0048 (5)	0.0042 (5)
C12	0.0392 (7)	0.0244 (6)	0.0325 (7)	−0.0081 (5)	−0.0100 (6)	0.0036 (5)
C13	0.0452 (8)	0.0230 (6)	0.0270 (6)	0.0013 (5)	−0.0084 (6)	−0.0017 (5)
C14	0.0329 (6)	0.0249 (6)	0.0227 (6)	0.0046 (5)	−0.0023 (5)	0.0022 (5)
C15	0.0228 (5)	0.0210 (5)	0.0209 (6)	0.0039 (4)	−0.0045 (4)	0.0037 (4)
C16	0.0190 (5)	0.0230 (5)	0.0235 (6)	0.0030 (4)	−0.0012 (4)	0.0048 (4)
C17	0.0182 (5)	0.0195 (5)	0.0260 (6)	−0.0008 (4)	−0.0011 (4)	0.0035 (4)
C18	0.0259 (6)	0.0275 (6)	0.0317 (7)	0.0020 (5)	0.0072 (5)	−0.0001 (5)
C19	0.0441 (8)	0.0337 (7)	0.0292 (7)	0.0033 (6)	0.0094 (6)	0.0065 (5)

Geometric parameters (Å, º) top

O1—C9	1.3736 (14)	C10—C15	1.4284 (16)
O1—C1	1.4381 (15)	C11—C12	1.3691 (18)
C1—C2	1.5034 (16)	C11—H11A	0.9500
C1—H1A	0.9900	C12—C13	1.403 (2)
C1—H1B	0.9900	C12—H12A	0.9500
C2—C3	1.3810 (15)	C13—C14	1.3666 (18)
C2—C10	1.4237 (16)	C13—H13A	0.9500
C3—C17	1.4189 (16)	C14—C15	1.4198 (16)
C3—C4	1.4728 (16)	C14—H14A	0.9500
C4—C5	1.3967 (16)	C15—C16	1.4307 (16)
C4—C9	1.3995 (16)	C16—C17	1.3676 (16)
C5—C6	1.3869 (17)	C16—C18	1.5105 (16)
C5—H5A	0.9500	C17—H17A	0.9500
C6—C7	1.3864 (18)	C18—C19	1.5281 (18)
C6—H6A	0.9500	C18—H18A	0.9900
C7—C8	1.3860 (18)	C18—H18B	0.9900
C7—H7A	0.9500	C19—H19A	0.9800
C8—C9	1.3857 (17)	C19—H19B	0.9800
C8—H8A	0.9500	C19—H19C	0.9800
C10—C11	1.4221 (16)

C9—O1—C1	114.65 (9)	C12—C11—C10	121.15 (12)
O1—C1—C2	112.50 (9)	C12—C11—H11A	119.4
O1—C1—H1A	109.1	C10—C11—H11A	119.4
C2—C1—H1A	109.1	C11—C12—C13	120.12 (12)
O1—C1—H1B	109.1	C11—C12—H12A	119.9
C2—C1—H1B	109.1	C13—C12—H12A	119.9
H1A—C1—H1B	107.8	C14—C13—C12	120.58 (12)
C3—C2—C10	120.27 (10)	C14—C13—H13A	119.7
C3—C2—C1	117.94 (10)	C12—C13—H13A	119.7
C10—C2—C1	121.69 (10)	C13—C14—C15	121.11 (12)
C2—C3—C17	119.33 (10)	C13—C14—H14A	119.4
C2—C3—C4	118.42 (10)	C15—C14—H14A	119.4
C17—C3—C4	122.25 (10)	C14—C15—C10	118.50 (11)
C5—C4—C9	117.57 (11)	C14—C15—C16	121.96 (11)
C5—C4—C3	124.21 (10)	C10—C15—C16	119.55 (10)
C9—C4—C3	118.19 (10)	C17—C16—C15	118.77 (10)
C6—C5—C4	121.42 (11)	C17—C16—C18	120.02 (10)
C6—C5—H5A	119.3	C15—C16—C18	121.17 (10)
C4—C5—H5A	119.3	C16—C17—C3	122.62 (10)
C7—C6—C5	119.62 (11)	C16—C17—H17A	118.7
C7—C6—H6A	120.2	C3—C17—H17A	118.7
C5—C6—H6A	120.2	C16—C18—C19	112.94 (10)
C8—C7—C6	120.35 (12)	C16—C18—H18A	109.0
C8—C7—H7A	119.8	C19—C18—H18A	109.0
C6—C7—H7A	119.8	C16—C18—H18B	109.0
C9—C8—C7	119.46 (12)	C19—C18—H18B	109.0
C9—C8—H8A	120.3	H18A—C18—H18B	107.8
C7—C8—H8A	120.3	C18—C19—H19A	109.5
O1—C9—C8	117.48 (11)	C18—C19—H19B	109.5
O1—C9—C4	120.86 (11)	H19A—C19—H19B	109.5
C8—C9—C4	121.57 (11)	C18—C19—H19C	109.5
C11—C10—C2	122.03 (11)	H19A—C19—H19C	109.5
C11—C10—C15	118.54 (11)	H19B—C19—H19C	109.5
C2—C10—C15	119.41 (10)

C9—O1—C1—C2	−48.75 (13)	C1—C2—C10—C11	2.20 (17)
O1—C1—C2—C3	33.77 (14)	C3—C2—C10—C15	−0.03 (16)
O1—C1—C2—C10	−150.00 (10)	C1—C2—C10—C15	−176.18 (10)
C10—C2—C3—C17	2.03 (16)	C2—C10—C11—C12	−177.98 (11)
C1—C2—C3—C17	178.33 (10)	C15—C10—C11—C12	0.41 (17)
C10—C2—C3—C4	−178.90 (10)	C10—C11—C12—C13	0.06 (19)
C1—C2—C3—C4	−2.61 (15)	C11—C12—C13—C14	−0.33 (19)
C2—C3—C4—C5	167.10 (11)	C12—C13—C14—C15	0.10 (19)
C17—C3—C4—C5	−13.87 (17)	C13—C14—C15—C10	0.38 (17)
C2—C3—C4—C9	−14.86 (15)	C13—C14—C15—C16	179.98 (11)
C17—C3—C4—C9	164.17 (10)	C11—C10—C15—C14	−0.62 (15)
C9—C4—C5—C6	−1.40 (17)	C2—C10—C15—C14	177.81 (10)
C3—C4—C5—C6	176.66 (10)	C11—C10—C15—C16	179.77 (10)
C4—C5—C6—C7	0.86 (18)	C2—C10—C15—C16	−1.80 (15)
C5—C6—C7—C8	0.10 (18)	C14—C15—C16—C17	−178.02 (11)
C6—C7—C8—C9	−0.48 (19)	C10—C15—C16—C17	1.57 (16)
C1—O1—C9—C8	−150.11 (11)	C14—C15—C16—C18	4.26 (16)
C1—O1—C9—C4	33.24 (15)	C10—C15—C16—C18	−176.14 (10)
C7—C8—C9—O1	−176.72 (11)	C15—C16—C17—C3	0.47 (17)
C7—C8—C9—C4	−0.09 (18)	C18—C16—C17—C3	178.21 (10)
C5—C4—C9—O1	177.52 (10)	C2—C3—C17—C16	−2.31 (17)
C3—C4—C9—O1	−0.65 (16)	C4—C3—C17—C16	178.67 (10)
C5—C4—C9—C8	1.01 (17)	C17—C16—C18—C19	−100.43 (13)
C3—C4—C9—C8	−177.16 (10)	C15—C16—C18—C19	77.25 (14)
C3—C2—C10—C11	178.35 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···O1ⁱ	0.99	2.49	3.3514 (14)	146

Symmetry code: (i) −x, −y+1, −z+1.

Acknowledgements

The University of Toronto thanks NSERC Canada for funding.

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