Crystal structure of methyl 2-(2H-1,3-benzodioxol-5-yl)-7,9-di­bromo-8-oxo-1-oxa­spiro­[4.5]deca-2,6,9-triene-3-car­boxyl­ate

Lucimara Julio Martins; Deborah de Alencar Simoni; Ricardo Aparicio; Fernando Coelho

doi:10.1107/S1600536814024763

. 2014 Nov 21;70(Pt 12):o1275–o1276. doi: 10.1107/S1600536814024763

Crystal structure of methyl 2-(2H-1,3-benzodioxol-5-yl)-7,9-dibromo-8-oxo-1-oxaspiro[4.5]deca-2,6,9-triene-3-carboxylate

Lucimara Julio Martins ^a, Deborah de Alencar Simoni ^b, Ricardo Aparicio ^c,^*, Fernando Coelho ^a

PMCID: PMC4257376 PMID: 25553042

Abstract

The title compound, C₁₈H₁₂Br₂O₆, was synthesized from Morita–Baylis–Hillman adducts. It incorporates the brominated spiro-hexadienone moiety typically exhibited by compounds of this class that exhibit biological activity. Both the brominated cyclohexadienone and the central five-membered rings are nearly planar (r.m.s. deviations of 0.044 and 0.016 Å, respectively), being almost perpendicularly oriented [interplanar angle = 89.47 (5)°]. With respect to the central five-membered ring, the brominated cyclohexadienone ring, the benzodioxol ring and the carboxylate fragment make C—O—C—C, O—C—C—C and C—C—C—O dihedral angles of −122.11 (8), −27.20 (11) and −8.40 (12)°, respectively. An intramolecular C—H⋯O hydrogen bond occurs. In the crystal, molecules are linked by non-classical C—H⋯O and C—H⋯Br hydrogen bonds resulting in a molecular packing in which the brominated rings are in a head-to-head orientation, forming well marked planes parallel to the b axis.

Keywords: Single-crystal X-ray study, spiro-hexadienone structure, Morita–Baylis–Hillman adducts

Related literature

For compounds that contain a spiro-hexadienone moiety in their structures, related biological activities and examples of brominated spiro-hexadienones, see: König & Wright (1993 ▶); Lou (2012 ▶); Sorek et al. (2009 ▶). For strategies for the synthesis of spiro-hexadienones from Morita–Baylis–Hillman aducts, see: Martins et al. (2014 ▶); Barontini et al. (2013 ▶).

Experimental

Crystal data

C₁₈H₁₂Br₂O₆
M _r = 484.10
Triclinic,
a = 8.1929 (13) Å
b = 8.4811 (14) Å
c = 12.761 (2) Å
α = 84.485 (4)°
β = 80.007 (5)°
γ = 78.077 (4)°
V = 852.7 (2) Å³
Z = 2
Mo Kα radiation
μ = 4.79 mm⁻¹
T = 100 K
0.32 × 0.17 × 0.16 mm

Data collection

Bruker APEX CCD detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2010 ▶) T _min = 0.309, T _max = 0.515
27788 measured reflections
7098 independent reflections
6288 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.018
wR(F ²) = 0.047
S = 1.02
7098 reflections
236 parameters
H-atom parameters constrained
Δρ_max = 0.57 e Å⁻³
Δρ_min = −0.39 e Å⁻³

Data collection: APEX2 (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2010 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXLE (Hübschle et al., 2011 ▶) and SHELXL2014 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2003 ▶), PLATON (Spek, 2009 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536814024763/hg5413sup1.cif

e-70-o1275-sup1.cif^{(810.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814024763/hg5413Isup2.hkl

e-70-o1275-Isup2.hkl^{(388.9KB, hkl)}

Click here for additional data file.^{(3.1KB, cdx)}

Supporting information file. DOI: 10.1107/S1600536814024763/hg5413Isup4.cdx

Click here for additional data file.^{(6KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814024763/hg5413Isup4.cml

Click here for additional data file.^{(1.8MB, tif)}

. DOI: 10.1107/S1600536814024763/hg5413fig1.tif

The molecular structure of the title compound with atom labels and 50% probability displacement ellipsoids.

Click here for additional data file.^{(1.6MB, tif)}

. DOI: 10.1107/S1600536814024763/hg5413fig2.tif

Crystal packing of the title compound, showing hydrogen bonding interactions.

CCDC reference: 1033626

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

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C3H3O5ⁱ	0.95	2.61	3.4272(13)	144
C7H7O5	0.95	2.34	2.9441(13)	121
C10H10AO1ⁱⁱ	0.99	2.55	3.3995(13)	143
C12H12ABr1ⁱⁱⁱ	0.99	2.96	3.9411(12)	173
C12H12AO1ⁱⁱⁱ	0.99	2.53	3.0852(13)	116
C13H13O2^iv	0.95	2.63	3.3909(13)	137
C16H16CO5^v	0.98	2.59	3.2434(14)	124
C17H17Br1^vi	0.95	3.03	3.9069(11)	153

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

Acknowledgments

The authors acknowledge Dr Jorge Henrique Monteiro for preliminary structure refinement. This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP 2009/18390–4 and 2009/51602–5), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). RA is the recipient of a research grant from CNPq.

supplementary crystallographic information

S1. Introduction

Compounds containing a spiro-hexadienone moiety typically exhibit biological activity, also sharing a structural architecture observed in some natural products (König & Wright, 1993; Sorek et al., 2009). In view of the importance of this class of compounds, recent efforts resulted in a new synthetic strategy, which starts from Morita-Baylis-Hillman adducts as building blocks for organic synthesis (Martins et al., 2014). Based on this methodology, it was possible to obtain a brominated spiro-hexadienone which resulted, to our knowledge, in the first report of a halogenated spiro-hexadienone crystal structure.

S2. Experimental

S2.1. Synthesis and crystallization

Methyl 2-(2H-1,3-benzodioxol-5-yl)-7,9-dibromo-8-oxo-1-oxaspiro[4.5]deca-2,6,9-triene-3-carboxylate was prepared from a subset of β-ketoesters following the experimental protocol recently described by Barontini et al. (2013). A separable mixture of mono- and dibrominated (in majority) derivatives in good overall yields was obtained.

After chromatographic separation, the dibrominated compounds were easily transformed into halogenated spiro-hexadienones, in three steps procedure, starting with the Morita-Baylis-Hillman adducts.

Methyl 2-(2H-1,3-benzodioxol-5-yl)-7,9-dibromo-8-oxo-1-oxaspiro[4.5]deca-2,6,9-triene-3-carboxylate (48 mg, 0.1 mmoL) was dissolved in absolute chloroform-D1 (1 mL), followed by stirring until total dissolution was achieved. The solution was kept in the freezer. After two weeks, the resulting material was filtered under vacuum, washed with small portions of cold chloroform and dried in a desiccator to furnish pale yellow single crystals suitable for X-ray diffraction data collection.

S2.2. Refinement

The C-bound H atoms were positioned with idealized geometry and treated as riding atoms: phenyl, methyl and methylene C—H bond lengths were 0.95, 0.98 and 0.99 Å, respectively. The isotropic displacement parameters values (U_iso(H)) were fixed at 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for all other attached H atoms.

S3. Results and discussion

The title compound (Fig. 1) crystallized in the space group P1 assuming a conformational structure determined by non-classical intramolecular C—H—O and intermolecular C—H—O and C—H—Br bonding (Table 1, Fig. 2). The molecule contains one six-membered (brominated ciclohexadienone) and one central five-membered rings connected by a spiro-carbon C4. The mean plane of these planar rings, C1—C2—C4—C17—C18 (r.m.s.= 0.044 Å) and C4—C10—C11—C5—O2 (r.m.s. = 0.016 Å), are almost perpendicularly oriented, making a plane-plane angle of 90.53°. With respect to the central five-membered ring, the brominated spiro-hexadienone and the benzodioxol rings make dihedral angles C5—O2—C4—C3 = -122.11 (8)° and O2—C5—C6—C14 = -27.20 (11)°, respectively, while the dihedral angle with the carboxylate fragment C10—C11—C15—O6 is -8.40 (12)°.

In the hexadienone ring of the title compound, the C2—C3, C17—C18 and C1—O1 bond lengths are 1.3351 (13), 1.3354 (13) and 1.2139 (11) Å, respectively, and the bond length between the spiro-carbon (C4) and the oxygen atom C4—O2 is 1.4684 (11) Å, similar to those reported for a related oxaspiro structure (Lou, 2012). In the latter, the plane-plane angle between the mean planes of the six-membered and the central five-membered rings in the spiro-carbon is 96.06°, slightly different from that observed in the title compound (90.53°). Further comparison also reveals different orientations of the carboxylate moiety, which makes a dihedral angle of 170.6 (1)° (C10—C11—C15—O5) in the title compound, with a corresponding angle equal to 11.3 (3)° in the related structure (Lou, 2012). This large difference is consistent with an observed C7—H7—O5 intramolecular hydrogen bond (Table 1) in the title compound, which results in a favourable conformation of the carboxylate group.