The 1:1 cocrystal of rac-7-oxabicyclo­[2.2.1]heptane-2,3-dicarboxylic acid and 2-amino­benzothia­zole

Yun-Yun Wang; Rui-Ding Hu; Yan-Jun Wang

doi:10.1107/S1600536808015365

. 2008 Jul 9;64(Pt 8):o1442. doi: 10.1107/S1600536808015365

The 1:1 cocrystal of rac-7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid and 2-aminobenzothiazole

Yun-Yun Wang ^a, Rui-Ding Hu ^a,^*, Yan-Jun Wang ^a

PMCID: PMC2962073 PMID: 21203157

Abstract

In the crystal structure of the title compound, rac-7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid–2-aminobenzothiazole (1/1), C₈H₁₀O₅·C₇H₆N₂S, molecules of each component are linked into centrosymmetric dimers by intermolecular N—H⋯O hydrogen bonds. These dimers are connected by O—H⋯O hydrogen bonds into a chain along the b axis. In addition, π–π interactions between aromatic heterocycles occur [centroid–centroid distance of 3.4709 Å and interplanar spacing of 3.4374 Å between symmetry-related benzothiazole ring systems.

Related literature

For related literature, see: Liu et al. (2002 ▶).

Experimental

Crystal data

C₈H₁₀O₅·C₇H₆N₂S
M _r = 336.36
Triclinic,
a = 8.3082 (1) Å
b = 9.0428 (1) Å
c = 11.0438 (2) Å
α = 67.1546 (8)°
β = 83.0101 (8)°
γ = 86.9193 (9)°
V = 758.92 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 296 (2) K
0.43 × 0.27 × 0.16 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.92, T _max = 0.96
11829 measured reflections
3416 independent reflections
2675 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.159
S = 1.06
3416 reflections
214 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.67 e Å⁻³
Δρ_min = −1.05 e Å⁻³

Data collection: SMART (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808015365/kp2168sup1.cif

e-64-o1442-sup1.cif^{(18KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808015365/kp2168Isup2.hkl

e-64-o1442-Isup2.hkl^{(167.5KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O1ⁱ	0.86	2.13	2.953 (3)	161
N1—H1B⋯O5	0.86	2.29	3.061 (3)	150
N1—H1B⋯O4	0.86	2.38	2.991 (3)	128
O2—H2⋯O4ⁱⁱ	0.836 (18)	1.868 (18)	2.700 (2)	174 (3)
O3—H3⋯N2ⁱ	0.854 (18)	1.758 (19)	2.611 (2)	176 (4)

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

Acknowledgments

The authors acknowledge financial support from the Natural Science Foundation of Zhejiang Province, China (grant No. Y407301).

supplementary crystallographic information

Comment

7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride (norcantharidin), a traditional Chinese drug, has great anti-cancer activity. In order to prepare compounds with pronounced anti-cancer activity, some derivatives were synthesized (Liu et al., 2002). 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride can react with 2-aminobenzothiazole to form an acylamide acid derivative which has strong anti-cancer activity. However, a crystal suitable for X-ray diffraction was obtained during the synthesis unexpectedly.

The crystal structure of the title compound (I) is characterized by alternating molecules of 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid and 2-aminobenzothiazole, linked by N—H···O and O—H···O hydrogen bonds. The centrosymmetric dimer composed of two 2-aminobenzothiazole and two acids is generated by bifurcated hydrogen bonds of amino group of 2-aminobenzothiazole and the acid component (N1—H1B···O4 and N1—H1B···O5, O3—H3···N2 and N1—H1A···O1). These dimers are connected into a chain by hydrogen bonds O2—H2···O4. Furthermore, there are short distances [centroid separation of 3.4709 Å and interplanar spacing of 3.4374 Å] between the benzothiazole-ring planes and the symmetry-related planes at (-x + 1,-y + 1,-z; -x + 1,-y + 2,-z) of adjacent chains, implying π···π interactions (Fig. 2). In the molecule, the conformation of 7-oxabicyclo[2.2.1]heptane ring is discussed as follows, the six-membered ring adopts a boat conformation and the two oxygen-bearing five-membered heterocycles are in an envelope conformation.

Experimental

7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride and 2-aminobenzothiazole were dissolved in acetonitrile and the mixture was stirred for 2 h at room temperature. The precipitate has been proved to exhibit anticancer activity. However, colourless crystals of (I) were obtained in the filtrate after several days, unexpectedly.