2-[(3S,3aS,5R,8S,8aS)-3,8-Di­methyl­hexa­hydro-1H,4H-3a,8a-ep­oxy­azulen-5-yl]propan-2-ol

Stacey Burrett; Dennis K Taylor; Edward R T Tiekink

doi:10.1107/S1600536814013543

. 2014 Jun 14;70(Pt 7):o776–o777. doi: 10.1107/S1600536814013543

2-[(3S,3aS,5R,8S,8aS)-3,8-Dimethylhexahydro-1H,4H-3a,8a-epoxyazulen-5-yl]propan-2-ol

Stacey Burrett ^a, Dennis K Taylor ^a, Edward R T Tiekink ^b,^*

PMCID: PMC4120619 PMID: 25161564

Abstract

Four independent molecules (A–D) comprise the asymmetric unit of the title compound, C₁₅H₂₆O₂, which differ only in the relative orientations of the terminal –C(Me)₂OH groups [e.g. the range of C_methylene—C_methine—C_quaternary—O_hydroxy torsion angles is 52.7 (7)–57.1 (6)°, where the C_methylene atom is bound to an epoxide C atom]. The five-membered rings adopt envelope conformations, with the methylene C atom adjacent to the methine C atom being the flap atom in each case. In each molecule, the conformation of the seven-membered ring is a half-chair, with the C_methylene—C_methine bond, flanked by methylene C atoms, being the back of the chair. Supramolecular helical chains along the b axis are found in the crystal packing, sustained by hydroxy–epoxide O—H⋯O hydrogen bonding. Molecules of A self-associate into a chain as do those of D. A third independent chain comprising B and C molecules is also formed. The studied crystal is a pseudo-merohedral twin (minor component ca 21%).

Related literature

For the preparation of the α- and β-epoxides of guaiol, see: Pesnelle (1966 ▶). graphic file with name e-70-0o776-scheme1.jpg

Experimental

Crystal data

C₁₅H₂₆O₂
M _r = 238.36
Monoclinic,
a = 7.4461 (1) Å
b = 11.0289 (2) Å
c = 33.7892 (6) Å
β = 90.579 (2)°
V = 2774.71 (8) Å³
Z = 8
Cu Kα radiation
μ = 0.57 mm⁻¹
T = 100 K
0.35 × 0.30 × 0.25 mm

Data collection

Agilent SuperNova Dual diffractometer with an Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2013 ▶) T _min = 0.666, T _max = 1.000
21600 measured reflections
10038 independent reflections
9883 reflections with I > 2σ(I)
R _int = 0.050

Refinement

R[F ² > 2σ(F ²)] = 0.102
wR(F ²) = 0.278
S = 1.02
10038 reflections
618 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.69 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2013 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) general, I. DOI: 10.1107/S1600536814013543/su2742sup1.cif

e-70-0o776-sup1.cif^{(46.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814013543/su2742Isup2.hkl

e-70-0o776-Isup2.hkl^{(490.9KB, hkl)}

CCDC reference: 1007725

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1ⁱ	0.84	1.99	2.804 (6)	162
O4—H4⋯O5ⁱⁱ	0.84	2.00	2.792 (7)	157
O6—H6⋯O3	0.84	1.99	2.821 (7)	171
O8—H8⋯O7ⁱⁱⁱ	0.84	2.00	2.795 (7)	158

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

This project was supported in part by the School of Agriculture, Food and Wine, The University of Adelaide, and by Australia’s grape growers and wine makers through their investment body, the Grape and Wine Research and Development Corporation, with matching funds from the Australian Government. SB thanks the Faculty of Science for a PhD scholarship. Intensity data were provided by the University of Malaya Crystallographic Laboratory. We thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR-MOHE/SC/03).

supplementary crystallographic information

S1. Chemical context

S2. Structural commentary

As has been reported previously (Pesnelle, 1966), the α and β-epoxides of guaiol have been prepared via the epoxidation of guaiol itself. In the present study suitable crystals for X-ray analysis of the minor product, β-epoxy guaiol (I), were isolated and the crystal structure is reported on herein.

Four independent molecules, A–D, comprise the crystallographic asymmetric unit of (I) with the O1-containing molecule shown in Fig. 1. As seen from the overlay diagram, Fig. 2, the four molecules are virtually superimposable with minor conformational differences noted in the relative orientations of the terminal -C(Me)₂OH group as seen, for example, in the values of the C11—C10—C13—O2 (molecule A) and C56—C55—C58—O8 (D) torsion angles of 57.1 (6) and 52.7 (7)°, respectively. In each case, the five-membered ring has an envelope conformation with the C3, C18, C33 and C48 atoms, i.e. the atom adjacent to the methine-C atom, being the flap atom. The seven-membered rings are best described as being based on a half-chair conformation. In this description, for molecule A, the C9 and C10 atoms lie 1.051 (11) and 1.297 (9) Å, respectively, out of the mean plane defined by the remaining five atoms, i.e. C5, C6, C8, C11 and C12 (r.m.s. deviation = 0.0514 Å). The corresponding values for molecule B are 1.063 (10), 1.309 (8) (r.m.s. deviation = 0.0564 Å); for molecule C 1.144 (12), 1.293 (9) (r.m.s. deviation = 0.0303 Å); and for molecule D 1.067 (10), 1.309 (9) (r.m.s. deviation = 0.0526 Å). Finally, the oxygen atoms lie to opposite sides of the molecule.

The most prominent feature of the crystal packing is the formation of hydroxyl-O—H···O(epoxide) hydrogen bonding, Table 1, that leads to helical supramolecular chains along the b axis. Molecules of A self-associate as illustrated in Fig. 3; molecules of D associate similarly. By contrast, molecules of B and C associate to form a third chain.

S3. Supramolecular features

S4. Database survey

S5. Synthesis and crystallization

A flask containing (-)-guaiol (4.01 g, 18 mmol) in dichloromethane (60 mL) was cooled to 273 K and peracetic acid in acetic acid (39%, 3.65 g, 18.7 mmol) was slowly added over 5 minutes. The mixture was stirred for an additional hour at 273 K and then washed with sodium bicarbonate (3 × 50 mL). The organic layer was dried over anhydrous MgSO₄ and concentrated in vacuum and the residue purified by column chromatography (10:90, ether/hexane) to afford both the α and β-epoxy guaiols in a ratio of approximately 60:40. The minor β-isomer was recrystallised at 253 K from a small amount of ether hexane (10:90) to afford the title compound (1.43 g, 33%) as white crystals. M. pt: 323–326 K. Lit. (Pesnelle, 1966) M. pt: 317-319 K, R_f = 0.31 (50:50, EtOAc/hexane). Spectroscopic data for the title compound are available in the archived CIF.

S6. Refinement

The H-atoms were placed in calculated positions and were included in the refinement in the riding model approximation: O—H = 0.84 Å, C—H = 0.95 - 1.00 Å with U_iso(H) = 1.5U_eq(O and C-methyl) and = 1.2U_eq(C) for other H atoms. The studied crystal is a pseudo-merohedral twin [the fractional contribution of the minor component refined to 0.210 (3)], precluding the determination of the absolute structure. The latter was assigned based on the chemistry, i.e. the use of (-)-guaiol as reagent. The maximum and minimum residual electron density peaks of 0.69 and 0.45 eÅ^-3, respectively, were located 1.02 Å and 0.76 Å from the O3 and C57 atoms, respectively.