(5R,6R)-rel-9-tert-Butyl-trans-5,6-dimeth­oxy-6,7-di­hydro-5H-benzo­cyclo­heptene

Lough, A.J.; Carlson, E.; Tam, W.

doi:10.1107/S2414314617014171

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 2| Part 10| October 2017| x171417

https://doi.org/10.1107/S2414314617014171

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(5R,6R)-rel-9-tert-Butyl-trans-5,6-dimethoxy-6,7-dihydro-5H-benzocycloheptene

Alan J. Lough,^a ^* Emily Carlson ^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: alough@chem.utoronto.ca

Edited by J. Simpson, University of Otago, New Zealand (Received 29 September 2017; accepted 2 October 2017; online 6 October 2017)

The relative stereochemistry of the title compound, C₁₇H₂₄O₂, has been confirmed by the X-ray analysis. The seven-membered ring is in a pseudo-boat conformation with both methoxy substituents in equatorial sites.

Keywords: crystal structure; relative stereochemistry; acid-catalysed ring-opening.

CCDC reference: 1577694

Structure description

In recent years, we have been investigating the acid-catalysed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadienes with alcohols (Tigchelaar et al., 2014 ). When bridgehead tert-butylated substrate I (Fig. 1) was reacted with methanol in the presence of catalytic para-toluenesulfonic acid, it was found that dihydro-5H-benzocycloheptene II was produced alongside methoxymethylnaphthalene III. The relative stereochemistry of the two methoxy groups in II was determined by this single-crystal X-ray analysis. Of the cis or trans isomers which were possible, the reaction was found to give solely the trans stereoisomer.

Figure 1
The reaction scheme.

The molecular structure of the title compound is shown in Fig. 2. The seven-membered ring is in a psuedo-boat conformation with atom C3 at the prow and atoms C6 and C11 forming the stern. Both methoxy substituents are in equatorial sites.

Figure 2
The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level.

Synthesis and crystallization

In a small screw-cap vial containing a stir-bar, cyclopropanated oxabenzonorbornadiene I (23.4 mg, 0.109 mmol, 1.0 equiv.) was dissolved in methanol (0.5 ml). The reaction was cooled to 273 K, and p-toluenesulfonic acid monohydrate (3.0 mg, 0.016 mmol, 0.1 equiv.) was added as a solid. The vial was sealed and heated to 313 K with continuous stirring for 48 h. The crude product was concentrated in vacuo and purified by column chromatography (EtOAc:hexanes=1:9), followed by static vacuum sublimation for two weeks over a 313–343 K gradient to give clear, colourless crystals of II.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₇H₂₄O₂
M_r	260.36
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	147
a, b, c (Å)	8.9716 (10), 9.5283 (10), 9.8080 (12)
α, β, γ (°)	80.493 (3), 73.205 (4), 69.547 (3)
V (Å³)	750.14 (15)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.07
Crystal size (mm)	0.33 × 0.29 × 0.20

Data collection
Diffractometer	Bruker Kappa APEX DUO CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2014 )
T_min, T_max	0.723, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	24158, 3493, 2784
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.654

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.040, 0.104, 1.03
No. of reflections	3493
No. of parameters	176
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.29, −0.24
Computer programs: APEX2 (and SAINT (Bruker, 2014), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), PLATON (Spek, 2009 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1577694

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314617014171/sj4137sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617014171/sj4137Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: APEX2 (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: publCIF (Westrip, 2010).

(5R,6R)-rel-9-tert-Butyl-trans-5,6-dimethoxy-6,7-dihydro-5H-benzocycloheptene top

Crystal data top

C₁₇H₂₄O₂	Z = 2
M_r = 260.36	F(000) = 284
Triclinic, P1	D_x = 1.153 Mg m⁻³
a = 8.9716 (10) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.5283 (10) Å	Cell parameters from 8137 reflections
c = 9.8080 (12) Å	θ = 2.5–27.5°
α = 80.493 (3)°	µ = 0.07 mm⁻¹
β = 73.205 (4)°	T = 147 K
γ = 69.547 (3)°	Block, colourless
V = 750.14 (15) Å³	0.33 × 0.29 × 0.20 mm

Data collection top

Bruker Kappa APEX DUO CCD diffractometer	2784 reflections with I > 2σ(I)
Radiation source: sealed tube with Bruker Triumph monochromator	R_int = 0.029
φ and ω scans	θ_max = 27.7°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −11→11
T_min = 0.723, T_max = 0.746	k = −12→12
24158 measured reflections	l = −12→12
3493 independent reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.040	H-atom parameters constrained
wR(F²) = 0.104	w = 1/[σ²(F_o²) + (0.0419P)² + 0.3109P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max < 0.001
3493 reflections	Δρ_max = 0.29 e Å⁻³
176 parameters	Δρ_min = −0.24 e Å⁻³

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.

Refinement. H atoms were placed in calculated positions with C–H = 0.95–1.00 Å and included in the refinement with U_iso(H)=1.2U_eq(C) or 1.5U_eq(C_methyl).

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

	x	y	z	U_iso*/U_eq
O1	0.25107 (11)	1.06653 (9)	0.84723 (9)	0.0240 (2)
O2	0.02295 (10)	1.05373 (9)	0.68789 (10)	0.0265 (2)
C1	0.26686 (14)	0.93904 (12)	0.77944 (12)	0.0183 (2)
H1A	0.1975	0.8816	0.8461	0.022*
C2	0.19875 (14)	0.99851 (13)	0.64668 (13)	0.0196 (2)
H2A	0.2412	1.0820	0.5954	0.023*
C3	0.24839 (15)	0.87513 (13)	0.54445 (13)	0.0221 (3)
H3A	0.1786	0.9087	0.4758	0.027*
H3B	0.3639	0.8585	0.4895	0.027*
C4	0.23111 (14)	0.72916 (13)	0.62286 (13)	0.0208 (2)
H4A	0.1425	0.6991	0.6178	0.025*
C5	0.33519 (14)	0.64025 (12)	0.69922 (12)	0.0183 (2)
C6	0.47614 (14)	0.68980 (13)	0.70089 (12)	0.0182 (2)
C7	0.64007 (15)	0.60102 (14)	0.65369 (13)	0.0230 (3)
H7A	0.6641	0.5045	0.6225	0.028*
C8	0.76832 (15)	0.65192 (15)	0.65179 (14)	0.0260 (3)
H8A	0.8789	0.5897	0.6205	0.031*
C9	0.73536 (15)	0.79289 (15)	0.69531 (14)	0.0257 (3)
H9A	0.8229	0.8269	0.6959	0.031*
C10	0.57333 (15)	0.88461 (14)	0.73825 (13)	0.0219 (3)
H10A	0.5508	0.9822	0.7663	0.026*
C11	0.44351 (14)	0.83514 (13)	0.74073 (12)	0.0180 (2)
C12	0.2426 (2)	1.03586 (17)	0.99566 (14)	0.0348 (3)
H12A	0.2318	1.1271	1.0366	0.052*
H12B	0.1471	1.0027	1.0433	0.052*
H12C	0.3429	0.9566	1.0094	0.052*
C13	−0.04585 (17)	1.20808 (15)	0.71351 (17)	0.0341 (3)
H13A	−0.1653	1.2393	0.7278	0.051*
H13B	0.0006	1.2672	0.6313	0.051*
H13C	−0.0205	1.2246	0.7991	0.051*
C14	0.30606 (15)	0.50389 (13)	0.79729 (14)	0.0221 (3)
C15	0.15674 (19)	0.47157 (17)	0.78247 (18)	0.0381 (4)
H15A	0.0587	0.5590	0.8079	0.057*
H15B	0.1419	0.3842	0.8464	0.057*
H15C	0.1737	0.4507	0.6836	0.057*
C16	0.2732 (2)	0.54034 (18)	0.95218 (16)	0.0406 (4)
H16A	0.3647	0.5677	0.9628	0.061*
H16B	0.2628	0.4521	1.0166	0.061*
H16C	0.1712	0.6245	0.9760	0.061*
C17	0.45407 (19)	0.36098 (16)	0.7681 (2)	0.0488 (5)
H17A	0.5472	0.3735	0.7920	0.073*
H17B	0.4838	0.3423	0.6669	0.073*
H17C	0.4259	0.2757	0.8267	0.073*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0318 (5)	0.0196 (4)	0.0224 (4)	−0.0064 (4)	−0.0091 (4)	−0.0059 (3)
O2	0.0193 (4)	0.0208 (4)	0.0385 (5)	−0.0004 (3)	−0.0108 (4)	−0.0066 (4)
C1	0.0194 (6)	0.0168 (5)	0.0192 (6)	−0.0047 (4)	−0.0055 (4)	−0.0041 (4)
C2	0.0187 (6)	0.0182 (5)	0.0211 (6)	−0.0031 (4)	−0.0069 (5)	−0.0025 (4)
C3	0.0252 (6)	0.0207 (6)	0.0207 (6)	−0.0030 (5)	−0.0102 (5)	−0.0037 (5)
C4	0.0194 (6)	0.0207 (6)	0.0236 (6)	−0.0044 (4)	−0.0066 (5)	−0.0075 (5)
C5	0.0166 (5)	0.0173 (5)	0.0200 (6)	−0.0034 (4)	−0.0024 (4)	−0.0065 (4)
C6	0.0170 (5)	0.0194 (5)	0.0174 (5)	−0.0046 (4)	−0.0057 (4)	0.0004 (4)
C7	0.0197 (6)	0.0215 (6)	0.0242 (6)	−0.0031 (5)	−0.0047 (5)	−0.0013 (5)
C8	0.0160 (6)	0.0322 (7)	0.0254 (6)	−0.0041 (5)	−0.0047 (5)	0.0011 (5)
C9	0.0206 (6)	0.0363 (7)	0.0234 (6)	−0.0136 (5)	−0.0077 (5)	0.0029 (5)
C10	0.0235 (6)	0.0248 (6)	0.0201 (6)	−0.0103 (5)	−0.0073 (5)	0.0003 (5)
C11	0.0184 (5)	0.0200 (6)	0.0154 (5)	−0.0058 (4)	−0.0056 (4)	0.0007 (4)
C12	0.0471 (9)	0.0370 (8)	0.0219 (7)	−0.0116 (6)	−0.0093 (6)	−0.0090 (6)
C13	0.0282 (7)	0.0242 (7)	0.0445 (8)	0.0020 (5)	−0.0086 (6)	−0.0116 (6)
C14	0.0194 (6)	0.0187 (6)	0.0273 (6)	−0.0055 (4)	−0.0051 (5)	−0.0017 (5)
C15	0.0379 (8)	0.0361 (8)	0.0498 (9)	−0.0231 (6)	−0.0172 (7)	0.0074 (7)
C16	0.0574 (10)	0.0447 (9)	0.0275 (7)	−0.0300 (8)	−0.0095 (7)	0.0048 (6)
C17	0.0337 (8)	0.0187 (7)	0.0731 (12)	−0.0022 (6)	0.0057 (8)	0.0053 (7)

Geometric parameters (Å, º) top

O1—C12	1.4218 (16)	C9—C10	1.3908 (18)
O1—C1	1.4248 (13)	C9—H9A	0.9500
O2—C13	1.4160 (15)	C10—C11	1.3939 (16)
O2—C2	1.4316 (14)	C10—H10A	0.9500
C1—C11	1.5218 (16)	C12—H12A	0.9800
C1—C2	1.5376 (16)	C12—H12B	0.9800
C1—H1A	1.0000	C12—H12C	0.9800
C2—C3	1.5334 (16)	C13—H13A	0.9800
C2—H2A	1.0000	C13—H13B	0.9800
C3—C4	1.5095 (17)	C13—H13C	0.9800
C3—H3A	0.9900	C14—C15	1.5252 (18)
C3—H3B	0.9900	C14—C17	1.5313 (18)
C4—C5	1.3388 (16)	C14—C16	1.5361 (19)
C4—H4A	0.9500	C15—H15A	0.9800
C5—C6	1.5014 (16)	C15—H15B	0.9800
C5—C14	1.5365 (17)	C15—H15C	0.9800
C6—C7	1.3997 (16)	C16—H16A	0.9800
C6—C11	1.4090 (16)	C16—H16B	0.9800
C7—C8	1.3907 (18)	C16—H16C	0.9800
C7—H7A	0.9500	C17—H17A	0.9800
C8—C9	1.3830 (19)	C17—H17B	0.9800
C8—H8A	0.9500	C17—H17C	0.9800

C12—O1—C1	113.00 (9)	C11—C10—H10A	119.6
C13—O2—C2	115.05 (10)	C10—C11—C6	119.80 (11)
O1—C1—C11	112.30 (9)	C10—C11—C1	120.67 (10)
O1—C1—C2	107.02 (9)	C6—C11—C1	119.47 (10)
C11—C1—C2	111.61 (9)	O1—C12—H12A	109.5
O1—C1—H1A	108.6	O1—C12—H12B	109.5
C11—C1—H1A	108.6	H12A—C12—H12B	109.5
C2—C1—H1A	108.6	O1—C12—H12C	109.5
O2—C2—C3	107.31 (9)	H12A—C12—H12C	109.5
O2—C2—C1	110.13 (10)	H12B—C12—H12C	109.5
C3—C2—C1	111.78 (9)	O2—C13—H13A	109.5
O2—C2—H2A	109.2	O2—C13—H13B	109.5
C3—C2—H2A	109.2	H13A—C13—H13B	109.5
C1—C2—H2A	109.2	O2—C13—H13C	109.5
C4—C3—C2	112.00 (10)	H13A—C13—H13C	109.5
C4—C3—H3A	109.2	H13B—C13—H13C	109.5
C2—C3—H3A	109.2	C15—C14—C17	107.98 (12)
C4—C3—H3B	109.2	C15—C14—C16	108.03 (12)
C2—C3—H3B	109.2	C17—C14—C16	108.57 (13)
H3A—C3—H3B	107.9	C15—C14—C5	111.73 (10)
C5—C4—C3	122.84 (11)	C17—C14—C5	112.59 (11)
C5—C4—H4A	118.6	C16—C14—C5	107.80 (10)
C3—C4—H4A	118.6	C14—C15—H15A	109.5
C4—C5—C6	116.82 (10)	C14—C15—H15B	109.5
C4—C5—C14	123.59 (11)	H15A—C15—H15B	109.5
C6—C5—C14	119.15 (10)	C14—C15—H15C	109.5
C7—C6—C11	118.47 (11)	H15A—C15—H15C	109.5
C7—C6—C5	122.24 (10)	H15B—C15—H15C	109.5
C11—C6—C5	119.11 (10)	C14—C16—H16A	109.5
C8—C7—C6	121.03 (11)	C14—C16—H16B	109.5
C8—C7—H7A	119.5	H16A—C16—H16B	109.5
C6—C7—H7A	119.5	C14—C16—H16C	109.5
C9—C8—C7	120.18 (11)	H16A—C16—H16C	109.5
C9—C8—H8A	119.9	H16B—C16—H16C	109.5
C7—C8—H8A	119.9	C14—C17—H17A	109.5
C8—C9—C10	119.61 (11)	C14—C17—H17B	109.5
C8—C9—H9A	120.2	H17A—C17—H17B	109.5
C10—C9—H9A	120.2	C14—C17—H17C	109.5
C9—C10—C11	120.85 (11)	H17A—C17—H17C	109.5
C9—C10—H10A	119.6	H17B—C17—H17C	109.5

C12—O1—C1—C11	−82.00 (13)	C6—C7—C8—C9	−0.77 (19)
C12—O1—C1—C2	155.18 (10)	C7—C8—C9—C10	−1.28 (19)
C13—O2—C2—C3	−147.34 (11)	C8—C9—C10—C11	1.29 (18)
C13—O2—C2—C1	90.77 (12)	C9—C10—C11—C6	0.74 (17)
O1—C1—C2—O2	−75.43 (11)	C9—C10—C11—C1	−176.41 (11)
C11—C1—C2—O2	161.33 (9)	C7—C6—C11—C10	−2.72 (17)
O1—C1—C2—C3	165.38 (9)	C5—C6—C11—C10	−177.88 (10)
C11—C1—C2—C3	42.13 (13)	C7—C6—C11—C1	174.46 (10)
O2—C2—C3—C4	−77.69 (12)	C5—C6—C11—C1	−0.69 (16)
C1—C2—C3—C4	43.16 (13)	O1—C1—C11—C10	−16.07 (15)
C2—C3—C4—C5	−73.62 (14)	C2—C1—C11—C10	104.12 (12)
C3—C4—C5—C6	−1.72 (17)	O1—C1—C11—C6	166.77 (10)
C3—C4—C5—C14	170.68 (11)	C2—C1—C11—C6	−73.04 (13)
C4—C5—C6—C7	−121.27 (13)	C4—C5—C14—C15	7.05 (17)
C14—C5—C6—C7	65.98 (15)	C6—C5—C14—C15	179.28 (11)
C4—C5—C6—C11	53.70 (15)	C4—C5—C14—C17	128.78 (14)
C14—C5—C6—C11	−119.05 (12)	C6—C5—C14—C17	−59.00 (16)
C11—C6—C7—C8	2.76 (18)	C4—C5—C14—C16	−111.50 (13)
C5—C6—C7—C8	177.75 (11)	C6—C5—C14—C16	60.73 (14)

Funding information

AJL thanks NSERC Canada for funding.

References

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