12,15-Dimethyl-8-oxa­tetra­cyclo­[8.8.0.0^2,7.0^11,16]octa­deca-1(18),2,4,6,11(16),12,14-heptaen-10-ol

In the title compound, he pyran ring is in a half-chair conformation and the fused ring system comprising the benzene and cyclo­hexene rings is essentially planar and forms a dihedral angle of 27.95 (6)° with the other benzene ring. In the crystal, O—H⋯O hydrogen bonds connect the mol­ecules into chains propagating along [001].

Abstract

In the title compound, C₁₉H₁₈O₂, the pyran ring is in a half-chair conformation. The fused ring system comprising the benzene and cyclo­hexene rings is essentially planar (r.m.s. deviation = 0.053 Å) and forms a dihedral angle of 27.95 (6)° with the other benzene ring. In the crystal, O—H⋯O hydrogen bonds connect the mol­ecules into chains propagating along [001].

Structure description

The ring-opening reaction of oxabenzonorbornadiene (OBD) has been well studied by many groups including our own (Lautens et al., 2003 ▸; Rayabarapu & Cheng, 2007 ▸; Boutin et al., 2019 ▸; Hill et al., 2019 ▸; Hill & Tam, 2019 ▸). Building on the work of Cheng (Duan & Cheng, 1995 ▸), our group has also demonstrated the palladium-catalysed regioselective ring-opening of C₁-substituted OBDs using aryl iodides (Raheem et al., 2014 ▸). However, to the best of our knowledge, intra­molecular modes of this reactivity have been left unexplored. Currently, the only known intra­molecular transformation of OBD was reported by the Lautens group (Loh et al., 2016 ▸) with a similar transformation recently reported by our group on cyclo­propanated OBD (Wicks et al., 2019 ▸). Based on this, we set out to investigate palladium-catalysed intra­molecular ring-openings of OBD with C₁-tethered aryl halides. The reaction of C₁-substituted OBD I (see Fig. 1 ▸) in the presence of PdCl₂(PPh₃)₂, Zn, Et₃N, and MeCN afforded an expected dehydrated product II in 82% yield, as well as an unexpected and yet unreported hydrated product III in 14% yield. The structure of the alcohol-containing fused tetra­cycle III was confirmed by single-crystal X-ray analysis.

Figure 1.

The reaction scheme

The mol­ecular structure of the title compound is shown in Fig. 2 ▸. The pyran ring (O1/C1/C2/C11/C12/C17) is in a half-chair conformation with atoms C1 and C2 deviating from the mean-plane of the other four atoms by −0.197 (2) and 0.556 (1) Å, respectively. The fused ring system comprising the benzene (C3–C8) and cyclo­hexene (C2/C3/C8–C11) rings is essentially planar (r.m.s. deviation = 0.053 Å) and forms a dihedral angle of 27.95 (6)° with the other benzene ring (C12–C17). In the arbitrarily chosen asymmetric unit, atom C2 has an S configuration but crystal symmetry generates a racemic mixture. In the crystal, O—H⋯O hydrogen bonds (Table 1 ▸) connect the mol­ecules into chains propagating along [001] (Fig. 3 ▸).

Figure 2.

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2O⋯O1i	0.86 (2)	2.03 (2)	2.8805 (14)	171.0 (19)

Symmetry code: (i) .

Figure 3.

Part of the crystal structure with O—H⋯O hydrogen bonds shown as dashed lines.

Synthesis and crystallization

To a 2 dram vial was added oxabenzonorbornadiene I (Fig. 1 ▸) (67.8 mg, 0.168 mmol), then purged with argon before importing into a glove box under an inert argon atmosphere. The vial was loaded sequentially with Zn (123.3 mg, 1.89 mmol, 11.2 eq.), MeCN (1.5 ml), Et₃N (0.09 ml, 0.669 mmol, 0.25 eq.) and PdCl₂(PPh₃)₂ (12.5 mg, 0.0178 mmol, 10.6 mol%), then exported and stirred at 333 K for 1 day. The mixture was cooled to room temperature and stirred in air for 10 minutes before removing the solvent under reduced pressure. The crude mixture was then purified by flash column chromatography using gradient elution (EtOAc:hexa­nes 1:9 to EtOAc:hexa­nes 1:4) to obtain the ring-opened product II (35.8 mg, 82%) as a white solid and III (6.6 mg, 14%) as a white solid. The product III was subsequently crystallized from methyl­ene chloride solution by slow evaporation to give product III as colourless crystals with orange specks.

Refinement

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

Table 2. Experimental details.

Crystal data
Chemical formula	C19H18O2
M r	278.33
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	150
a, b, c (Å)	12.2712 (7), 11.2934 (6), 10.8984 (7)
β (°)	112.565 (2)
V (Å3)	1394.71 (14)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.09
Crystal size (mm)	0.25 × 0.19 × 0.11
Data collection
Diffractometer	Bruker Kappa APEX DUO CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 ▸)
T min, T max	0.703, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	22859, 3212, 2404
R int	0.040
(sin θ/λ)max (Å−1)	0.650
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.040, 0.110, 1.04
No. of reflections	3212
No. of parameters	196
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.31, −0.22

Computer programs: APEX3 (Bruker, 2018 ▸), SAINT (Bruker, 2018 ▸), SHELXT2014 (Sheldrick, 2015a ▸), SHELXL2018 (Sheldrick, 2015b ▸), PLATON (Spek, 2020 ▸), publCIF (Westrip, 2010 ▸).

Supplementary Material

CCDC reference: 1988571

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

full crystallographic data

Crystal data

C19H18O2	F(000) = 592
Mr = 278.33	Dx = 1.326 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.2712 (7) Å	Cell parameters from 6674 reflections
b = 11.2934 (6) Å	θ = 2.6–27.5°
c = 10.8984 (7) Å	µ = 0.09 mm−1
β = 112.565 (2)°	T = 150 K
V = 1394.71 (14) Å3	Shard, colourless
Z = 4	0.25 × 0.19 × 0.11 mm

Data collection

Bruker Kappa APEX DUO CCD diffractometer	2404 reflections with I > 2σ(I)
Radiation source: sealed tube with Bruker Triumph monochromator	Rint = 0.040
φ and ω scans	θmax = 27.5°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −15→15
Tmin = 0.703, Tmax = 0.746	k = −14→12
22859 measured reflections	l = −14→14
3212 independent reflections

Refinement

Refinement on F2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.040	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.110	w = 1/[σ2(Fo2) + (0.0478P)2 + 0.6316P] where P = (Fo2 + 2Fc2)/3
S = 1.03	(Δ/σ)max < 0.001
3212 reflections	Δρmax = 0.31 e Å−3
196 parameters	Δρmin = −0.21 e Å−3
0 restraints

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.38362 (9)	0.71483 (9)	0.94095 (10)	0.0227 (2)
O2	0.35317 (9)	0.79851 (9)	0.68983 (10)	0.0195 (2)
H2O	0.3639 (17)	0.8028 (17)	0.616 (2)	0.041 (6)*
C1	0.28530 (12)	0.67697 (13)	0.82436 (13)	0.0194 (3)
H1A	0.216856	0.729079	0.811291	0.023*
H1B	0.263028	0.595336	0.838378	0.023*
C2	0.31342 (12)	0.67990 (12)	0.69883 (13)	0.0165 (3)
C3	0.20305 (12)	0.64875 (12)	0.57662 (13)	0.0168 (3)
C4	0.10115 (12)	0.72098 (12)	0.54010 (14)	0.0183 (3)
C5	−0.00046 (13)	0.68454 (13)	0.43491 (14)	0.0207 (3)
H5A	−0.070186	0.730804	0.411431	0.025*
C6	−0.00220 (13)	0.58267 (13)	0.36392 (14)	0.0217 (3)
H6A	−0.073619	0.558560	0.294864	0.026*
C7	0.09851 (13)	0.51547 (13)	0.39205 (14)	0.0204 (3)
C8	0.20197 (12)	0.54850 (12)	0.49950 (14)	0.0185 (3)
C9	0.31027 (13)	0.47357 (14)	0.52591 (15)	0.0266 (3)
H9A	0.289357	0.389843	0.532701	0.032*
H9B	0.333308	0.479937	0.448491	0.032*
C10	0.41426 (13)	0.50446 (14)	0.64767 (15)	0.0230 (3)
H10A	0.482918	0.456604	0.670766	0.028*
C11	0.41632 (12)	0.59543 (12)	0.72595 (13)	0.0182 (3)
C12	0.51602 (12)	0.61900 (12)	0.85341 (14)	0.0188 (3)
C13	0.63234 (13)	0.58519 (13)	0.87853 (15)	0.0235 (3)
H13A	0.649773	0.547125	0.810468	0.028*
C14	0.72254 (13)	0.60601 (14)	1.00035 (16)	0.0266 (3)
H14A	0.800938	0.582302	1.015531	0.032*
C15	0.69775 (13)	0.66181 (14)	1.10041 (16)	0.0258 (3)
H15A	0.759337	0.675389	1.184465	0.031*
C16	0.58418 (13)	0.69762 (13)	1.07837 (15)	0.0231 (3)
H16A	0.567555	0.736584	1.146479	0.028*
C17	0.49430 (12)	0.67609 (13)	0.95542 (14)	0.0192 (3)
C18	0.09345 (14)	0.83818 (14)	0.60380 (16)	0.0255 (3)
H18A	0.172468	0.872790	0.644921	0.038*
H18B	0.060772	0.825342	0.671871	0.038*
H18C	0.042111	0.892264	0.535837	0.038*
C19	0.09555 (14)	0.40895 (14)	0.30771 (15)	0.0271 (3)
H19A	0.154520	0.418330	0.268138	0.041*
H19B	0.016948	0.401618	0.237010	0.041*
H19C	0.113242	0.337581	0.363080	0.041*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0194 (5)	0.0335 (6)	0.0143 (5)	0.0017 (4)	0.0056 (4)	−0.0035 (4)
O2	0.0245 (5)	0.0175 (5)	0.0182 (5)	−0.0023 (4)	0.0100 (4)	−0.0002 (4)
C1	0.0176 (7)	0.0263 (8)	0.0140 (7)	−0.0015 (6)	0.0059 (5)	−0.0003 (5)
C2	0.0197 (7)	0.0162 (7)	0.0141 (6)	−0.0010 (5)	0.0071 (5)	−0.0006 (5)
C3	0.0191 (7)	0.0186 (7)	0.0136 (6)	−0.0012 (5)	0.0073 (5)	0.0013 (5)
C4	0.0223 (7)	0.0181 (7)	0.0162 (7)	0.0000 (6)	0.0091 (6)	0.0019 (5)
C5	0.0203 (7)	0.0231 (8)	0.0182 (7)	0.0023 (6)	0.0068 (6)	0.0035 (6)
C6	0.0220 (7)	0.0255 (8)	0.0146 (7)	−0.0036 (6)	0.0036 (6)	0.0013 (6)
C7	0.0264 (7)	0.0195 (7)	0.0155 (7)	−0.0032 (6)	0.0083 (6)	0.0001 (5)
C8	0.0223 (7)	0.0183 (7)	0.0160 (7)	−0.0010 (5)	0.0085 (6)	0.0000 (5)
C9	0.0279 (8)	0.0252 (8)	0.0239 (8)	0.0039 (6)	0.0068 (6)	−0.0078 (6)
C10	0.0225 (7)	0.0247 (8)	0.0214 (7)	0.0041 (6)	0.0079 (6)	−0.0007 (6)
C11	0.0192 (7)	0.0202 (7)	0.0159 (7)	0.0005 (5)	0.0076 (5)	0.0024 (5)
C12	0.0206 (7)	0.0179 (7)	0.0176 (7)	−0.0003 (6)	0.0071 (6)	0.0021 (5)
C13	0.0231 (7)	0.0234 (8)	0.0243 (8)	0.0018 (6)	0.0094 (6)	0.0022 (6)
C14	0.0194 (7)	0.0278 (8)	0.0298 (8)	0.0025 (6)	0.0065 (6)	0.0041 (7)
C15	0.0229 (8)	0.0256 (8)	0.0221 (8)	−0.0028 (6)	0.0010 (6)	0.0033 (6)
C16	0.0263 (8)	0.0242 (8)	0.0177 (7)	−0.0018 (6)	0.0073 (6)	0.0003 (6)
C17	0.0189 (7)	0.0203 (7)	0.0180 (7)	−0.0001 (5)	0.0064 (6)	0.0032 (6)
C18	0.0250 (8)	0.0242 (8)	0.0245 (8)	0.0053 (6)	0.0063 (6)	−0.0030 (6)
C19	0.0320 (9)	0.0247 (8)	0.0215 (8)	−0.0029 (6)	0.0070 (6)	−0.0061 (6)

Geometric parameters (Å, º)

O1—C17	1.3771 (17)	C9—H9A	0.9900
O1—C1	1.4410 (17)	C9—H9B	0.9900
O2—C2	1.4417 (17)	C10—C11	1.329 (2)
O2—H2O	0.86 (2)	C10—H10A	0.9500
C1—C2	1.5343 (18)	C11—C12	1.4809 (19)
C1—H1A	0.9900	C12—C17	1.397 (2)
C1—H1B	0.9900	C12—C13	1.399 (2)
C2—C11	1.5184 (19)	C13—C14	1.384 (2)
C2—C3	1.5322 (19)	C13—H13A	0.9500
C3—C8	1.4071 (19)	C14—C15	1.390 (2)
C3—C4	1.4162 (19)	C14—H14A	0.9500
C4—C5	1.393 (2)	C15—C16	1.381 (2)
C4—C18	1.514 (2)	C15—H15A	0.9500
C5—C6	1.382 (2)	C16—C17	1.392 (2)
C5—H5A	0.9500	C16—H16A	0.9500
C6—C7	1.381 (2)	C18—H18A	0.9800
C6—H6A	0.9500	C18—H18B	0.9800
C7—C8	1.408 (2)	C18—H18C	0.9800
C7—C19	1.506 (2)	C19—H19A	0.9800
C8—C9	1.507 (2)	C19—H19B	0.9800
C9—C10	1.487 (2)	C19—H19C	0.9800
C17—O1—C1	117.52 (11)	H9A—C9—H9B	107.5
C2—O2—H2O	107.0 (13)	C11—C10—C9	123.53 (14)
O1—C1—C2	112.41 (11)	C11—C10—H10A	118.2
O1—C1—H1A	109.1	C9—C10—H10A	118.2
C2—C1—H1A	109.1	C10—C11—C12	123.11 (13)
O1—C1—H1B	109.1	C10—C11—C2	123.44 (13)
C2—C1—H1B	109.1	C12—C11—C2	113.31 (12)
H1A—C1—H1B	107.9	C17—C12—C13	117.53 (13)
O2—C2—C11	108.61 (11)	C17—C12—C11	119.23 (12)
O2—C2—C3	111.32 (11)	C13—C12—C11	123.23 (13)
C11—C2—C3	114.62 (11)	C14—C13—C12	121.44 (14)
O2—C2—C1	106.17 (11)	C14—C13—H13A	119.3
C11—C2—C1	105.53 (11)	C12—C13—H13A	119.3
C3—C2—C1	110.11 (11)	C13—C14—C15	119.62 (14)
C8—C3—C4	119.39 (13)	C13—C14—H14A	120.2
C8—C3—C2	120.44 (12)	C15—C14—H14A	120.2
C4—C3—C2	120.18 (12)	C16—C15—C14	120.41 (14)
C5—C4—C3	118.42 (13)	C16—C15—H15A	119.8
C5—C4—C18	116.22 (13)	C14—C15—H15A	119.8
C3—C4—C18	125.34 (13)	C15—C16—C17	119.37 (14)
C6—C5—C4	121.55 (13)	C15—C16—H16A	120.3
C6—C5—H5A	119.2	C17—C16—H16A	120.3
C4—C5—H5A	119.2	O1—C17—C16	115.93 (13)
C7—C6—C5	120.87 (13)	O1—C17—C12	122.45 (12)
C7—C6—H6A	119.6	C16—C17—C12	121.62 (13)
C5—C6—H6A	119.6	C4—C18—H18A	109.5
C6—C7—C8	118.93 (13)	C4—C18—H18B	109.5
C6—C7—C19	119.58 (13)	H18A—C18—H18B	109.5
C8—C7—C19	121.49 (13)	C4—C18—H18C	109.5
C3—C8—C7	120.59 (13)	H18A—C18—H18C	109.5
C3—C8—C9	122.15 (13)	H18B—C18—H18C	109.5
C7—C8—C9	117.25 (13)	C7—C19—H19A	109.5
C10—C9—C8	115.51 (12)	C7—C19—H19B	109.5
C10—C9—H9A	108.4	H19A—C19—H19B	109.5
C8—C9—H9A	108.4	C7—C19—H19C	109.5
C10—C9—H9B	108.4	H19A—C19—H19C	109.5
C8—C9—H9B	108.4	H19B—C19—H19C	109.5
C17—O1—C1—C2	−41.25 (17)	C7—C8—C9—C10	−174.41 (13)
O1—C1—C2—O2	−54.75 (14)	C8—C9—C10—C11	−3.5 (2)
O1—C1—C2—C11	60.43 (14)	C9—C10—C11—C12	174.19 (14)
O1—C1—C2—C3	−175.37 (11)	C9—C10—C11—C2	−1.2 (2)
O2—C2—C3—C8	123.95 (13)	O2—C2—C11—C10	−122.26 (14)
C11—C2—C3—C8	0.19 (18)	C3—C2—C11—C10	2.93 (19)
C1—C2—C3—C8	−118.58 (14)	C1—C2—C11—C10	124.26 (15)
O2—C2—C3—C4	−55.88 (16)	O2—C2—C11—C12	61.99 (14)
C11—C2—C3—C4	−179.64 (11)	C3—C2—C11—C12	−172.82 (11)
C1—C2—C3—C4	61.59 (16)	C1—C2—C11—C12	−51.50 (14)
C8—C3—C4—C5	5.28 (19)	C10—C11—C12—C17	−150.86 (15)
C2—C3—C4—C5	−174.89 (12)	C2—C11—C12—C17	24.91 (18)
C8—C3—C4—C18	−172.91 (13)	C10—C11—C12—C13	28.1 (2)
C2—C3—C4—C18	6.9 (2)	C2—C11—C12—C13	−156.10 (13)
C3—C4—C5—C6	−2.2 (2)	C17—C12—C13—C14	0.8 (2)
C18—C4—C5—C6	176.20 (13)	C11—C12—C13—C14	−178.20 (14)
C4—C5—C6—C7	−2.3 (2)	C12—C13—C14—C15	−0.1 (2)
C5—C6—C7—C8	3.6 (2)	C13—C14—C15—C16	−0.7 (2)
C5—C6—C7—C19	−176.41 (13)	C14—C15—C16—C17	0.8 (2)
C4—C3—C8—C7	−4.1 (2)	C1—O1—C17—C16	−169.75 (12)
C2—C3—C8—C7	176.07 (12)	C1—O1—C17—C12	10.5 (2)
C4—C3—C8—C9	174.87 (13)	C15—C16—C17—O1	−179.75 (13)
C2—C3—C8—C9	−5.0 (2)	C15—C16—C17—C12	0.0 (2)
C6—C7—C8—C3	−0.3 (2)	C13—C12—C17—O1	178.97 (13)
C19—C7—C8—C3	179.64 (13)	C11—C12—C17—O1	−2.0 (2)
C6—C7—C8—C9	−179.36 (13)	C13—C12—C17—C16	−0.8 (2)
C19—C7—C8—C9	0.6 (2)	C11—C12—C17—C16	178.27 (13)
C3—C8—C9—C10	6.6 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O1i	0.86 (2)	2.03 (2)	2.8805 (14)	171.0 (19)

Symmetry code: (i) x, −y+3/2, z−1/2.