Ethyl 5-hy­droxy-6-oxo-4-phenyl-5,6-dihydro-4H-cyclo­penta­[b]thio­phene-5-carboxyl­ate

C John McAdam; Stephen C Moratti; Jim Simpson; Zheng Shi

doi:10.1107/S1600536811037032

. 2011 Sep 30;67(Pt 10):o2764–o2765. doi: 10.1107/S1600536811037032

Ethyl 5-hydroxy-6-oxo-4-phenyl-5,6-dihydro-4H-cyclopenta[b]thiophene-5-carboxylate

C John McAdam ^a, Stephen C Moratti ^a, Jim Simpson ^a,^*, Zheng Shi ^a

PMCID: PMC3201281 PMID: 22058815

Abstract

In the title molecule, C₁₆H₁₄O₄S, the dihydrocyclopentathiophenone ring system is almost planar, with an r.m.s. deviation of 0.060 Å from the best fit plane through all nine non-H atoms. The cyclopentanone ring adopts a severely flattened envelope conformation with the C atom carrying the OH and ethylcarboxylate substituents at the flap. This atom lies only 0.185 (3) Å from the plane through the other four C atoms. The phenyl substituent is inclined at 43.37 (5)° to the dihydrocyclopentathiophenone mean plane. In the crystal, molecules are linked by pairs of O—H⋯O hydrogen bonds, forming inversion dimers with R ₂ ²(10) ring motifs. Weak C—H⋯O hydrogen bonds also link molecules into chains along c, while an approximately orthogonal set of C—H⋯O contacts form chains along b, resulting in layers lying parallel to (100). Inversion dimers also form through weaker R ₂ ²(12) C—H⋯S contacts, which combine with C—H⋯O contacts to form stacks along b.

Related literature

For details of conducting thiophene polymers, see: Anquetil et al. (2003 ▶). For related structures, see: Bonini et al. (2004 ▶); Chang et al. (2004 ▶). For details of the Cambridge Structural Database, see: Allen (2002 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For standard bond lengths, see Allen et al. (1987 ▶). For the preparation of a precursor used in the synthesis, see: Yang (2009 ▶).

Experimental

Crystal data

C₁₆H₁₄O₄S
M _r = 302.33
Triclinic,
a = 7.7407 (4) Å
b = 9.1005 (4) Å
c = 10.5035 (5) Å
α = 84.840 (3)°
β = 80.929 (3)°
γ = 88.086 (3)°
V = 727.56 (6) Å³
Z = 2
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 91 K
0.45 × 0.35 × 0.25 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2011 ▶) T _min = 0.672, T _max = 0.745
13007 measured reflections
2584 independent reflections
2233 reflections with I > 2σ(I)
R _int = 0.035

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.079
S = 1.07
2584 reflections
194 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: APEX2 (Bruker, 2011 ▶); cell refinement: APEX2 and SAINT (Bruker, 2011 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶) and TITAN2000 (Hunter & Simpson, 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and TITAN2000; molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXL97, enCIFer (Allen et al., 2004 ▶), PLATON (Spek, 2009 ▶) and publCIF (Westrip 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811037032/su2314sup1.cif

e-67-o2764-sup1.cif^{(22KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811037032/su2314Isup2.hkl

e-67-o2764-Isup2.hkl^{(126.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811037032/su2314Isup3.cml

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
O6—H6⋯O14	0.82 (2)	2.27 (2)	2.6705 (16)	110.8 (16)
O6—H6⋯O5ⁱ	0.82 (2)	2.06 (2)	2.7973 (16)	150.5 (19)
C1—H1⋯O14ⁱⁱ	0.95	2.56	3.157 (2)	121
C11—H11⋯O5ⁱⁱⁱ	0.95	2.52	3.386 (2)	152
C15—H15B⋯O6^iv	0.99	2.27	3.206 (2)	157
C7—H7⋯S1^v	1.00	2.97	3.7855 (16)	139
C12—H12⋯O14^vi	0.95	2.61	3.497 (2)	157

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

Acknowledgments

We thank the New Economy Research Fund (grant No. UOO-X0808) for support of this work and the University of Otago for the purchase of the diffractometer.

supplementary crystallographic information

Comment

There is currently much interest in research into conducting thiophene polymers (Anquetil et al., 2003). Our interest in molecular actuators based on this chemistry led to the isolation of the previously unreported title compound.

In the molecular structure of the title molecule (Fig. 1), the flap atom of the severely flattened C3···C7 ring carries both hydroxy and ethylcarboxylate substituents. Atom C6 lies 0.185 (3) Å from the mean plane through atoms (C3-C5,C7) and this plane is inclined at 4.43 (8) ° to the thiophene ring (S1,C1-C4) mean plane. As a result the dihydrocyclopenta-thiophene-one ring system is also reasonably planar with a r.m.s. deviation of only 0.060 Å from the plane through all 9 non-hydrogen atoms. The C7 atom of the cyclopentane ring carries a phenyl substituent that subtends a dihedral angle of 43.37 (5) ° to the dihydrocyclopentathiophene plane. The Cambridge Crystal Structure Database (CSD, Version 5.32, last update Aug. 2011; Allen, 2002) reveals only three structures involving dihydrocyclopenta-thiophene-one ring systems (Bonini et al., 2004; Chang et al., 2004). In the title molecule the bond distances are normal (Allen et al., 1987) and similar to those reported for these similar molecules.

In the crystal O6–H6···O5 hydrogen bonds form inversion dimers with R²₂(10) ring motifs, (Bernstein et al., 1995), Fig 2. Chains form along c due to weak C11–H11···O5 contacts while C1–H1..O14 contacts form chains at roughly 90 ° to these along b. These contacts combine to generate layers lying parallel to the (100) plane, Fig 3. Inversion dimers also form through weaker R²₂(12) C7–H7···S1 contacts, and together with C12..H12···O14 hydrogen bonds lead to stacks along b, Fig 4. Additional C15..H15···O6 contacts further stabilize the packing.

Experimental

The precursor thiophene, ethyl 6-oxo-4-phenyl-5,6-dihydro-4H-cyclopenta- thiophene-5-carboxylate (EOPDCTC), was prepared by a literature procedure (Yang, 2009). EOPDCTC (315 mg, 1.1 mmol) and potassium tertiary butoxide (289 mg, 2.6 mmol) were dissolved in 2-propanol (5 ml) and iodine (280 mg, 1.1 mmol) in 2-propanol (5 ml) added dropwise under a N₂ atmosphere. After stirring at room temperature for 24 hrs, the solvent was removed under reduced pressure. The residues were redissolved in EtOAc, washed with saturated sodium thiosulfate and distilled water then dried over MgSO₄. The crude product was purified by silica gel column chromatography with CH₂Cl₂/EtOAc (10%) to give a brown solid in 17% yield. X-ray quality crystals were obtained from a CH₂Cl₂ solution of the title compound layered with hexane. M.p 404 K. HRMS (+ve ESI) m/z calc for C₁₆H₁₃O₄SNa 324.0427, found 325.1152. Spectroscopic data for the title compound are available in the archived CIF.