(3-Chloro­phen­yl){2-eth­oxy-5-[(Z)-hydroxy(phen­yl)methyl­idene]cyclo­penta-1,3-dien-1-yl}methanone

Mihaela-Liliana Tinţaş; Richard A Varga; Ion Grosu; Elena Bogdan

doi:10.1107/S1600536811055279

. 2012 Jan 11;68(Pt 2):o310–o311. doi: 10.1107/S1600536811055279

(3-Chlorophenyl){2-ethoxy-5-[(Z)-hydroxy(phenyl)methylidene]cyclopenta-1,3-dien-1-yl}methanone

Mihaela-Liliana Tinţaş ^a, Richard A Varga ^b, Ion Grosu ^a, Elena Bogdan ^a,^*

PMCID: PMC3275002 PMID: 22346947

Abstract

The title compound, C₂₁H₁₇ClO₃, which crystallizes as one of two possible oxo/hydroxy-fulvene prototropic tautomers, possesses a strong intramolecular O—H⋯O hydrogen bond that closes a seven-membered ring. The dihedral angles between the central five-membered ring and two pendant rings are 55.05 (9) and 44.51 (10)°. The crystal packing is characterized by weak intermolecular C—H⋯O interactions between an H atom of the oxymethylene unit and the carbonyl group of an adjacent molecule, resulting in formation of chains of molecules along the a axis.

Related literature

For the structures of related 2-acyl-6-hydoxyfulvene derivatives, see: Ferguson et al. (1975 ▶); Dong et al. (2004 ▶, 2006 ▶). For more information on the synthesis of 2-acyl-6-hydoxyfulvene derivatives, see: Dong et al. (2004 ▶, 2006 ▶). For preparation details, see: Christl et al. (1998 ▶). For compounds obtained from 2-acyl-6-hydoxyfulvenes, see: Dong et al. (2004 ▶); Li et al. (2008 ▶); Snyder et al. (2005 ▶). For complexes based on 2-acyl-6-hydoxyfulvenes, see: Dong et al. (2004 ▶, 2006 ▶); Wang et al. (2005 ▶). For their various applications, see: Hong et al. (2005 ▶); Kondo et al. (1992 ▶); Vicente et al. (1995 ▶).

Experimental

Crystal data

C₂₁H₁₇ClO₃
M _r = 352.80
Monoclinic,
a = 8.1369 (16) Å
b = 27.737 (6) Å
c = 7.6709 (15) Å
β = 98.51 (3)°
V = 1712.2 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 297 K
0.30 × 0.29 × 0.26 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.932, T _max = 0.940
15678 measured reflections
3002 independent reflections
2683 reflections with I > 2σ(I)
R _int = 0.040

Refinement

R[F ² > 2σ(F ²)] = 0.061
wR(F ²) = 0.125
S = 1.17
3002 reflections
231 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT-Plus (Bruker, 2000 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811055279/ld2041sup1.cif

e-68-0o310-sup1.cif^{(24.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811055279/ld2041Isup2.hkl

e-68-0o310-Isup2.hkl^{(147.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811055279/ld2041Isup3.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
O1—H1⋯O2	1.07 (5)	1.38 (5)	2.435 (3)	168 (5)
C20—H20B⋯O2ⁱ	0.97	2.51	3.246 (3)	133

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by the CNCS–UEFISCDI, project No. PN II_IDEI_2278/2008.

supplementary crystallographic information

Comment

Widely used as synthetic precursors, fulvenes are key intermediates in the total synthesis of several natural products (Hong et al. 2005, Vicente et al. 1995) and are well known as one of the important organic ligands used in construction of organometalic complexes (Li et al. 2008, Dong et al. 2006, Snyder et al. 2005, Wang et al. 2005, Dong et al. 2004). Fulvenes also raised interest due to their potential as non-linear optic materials (Kondo et al. 1992).

The title compound was obtained as a by-product in the oxidation reaction of dihydro-α-pyrone 1-(3-chlorophenyl)-4-phenyl-4a,5-dihydrocyclopenta[c]pyran-3(4H)-one with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) in chloroform (Christl et al. 1998). We observed that during the dehydrogenation process in order to obtain the corresponding α-pyrone, a competitive reaction underwent with formation of the fulvene derivative (Fig. 1) only when chloroform containing 0.5–1% ethanol as stabilizer is used as solvent. By performing the oxidation reaction in ethanol free of chloroform, no fulvene structure of the title compound could be identified.

In the molecule of the title compound (Fig. 1), the C—C bond lenghts of the five-membered ring as well as C13—C14 and C15—C19 range from 1.366 (3) to 1.481 (7) Å, corresponding to a delocalized system extended from C═O to the enol OH group (Ferguson et al. 1975). The hydroxy-fulvene tautomer is favored by the strong intramolecular H-bonding of the enol hydrogen atom H1 and the carbonyl oxygen atom O2, [H1···O2 = 1.38 (5) Å, O1—H1···O2 = 168 (5)°]. Thus a H-bonded seven-membered ring almost coplanar with the five-membered one is formed. The two aryl units attached at C13 and C19 are almost orthogonal disposed, the dihedral angles between the phenyl and m-chlorophenylene with respect to the seven-membered ring plane being 44.4 (9) and 54.4 (0)° respectively.

The crystal packing (Fig. 2) is stabilized by weak intermolecular C—H···O hydrogen bonds, therefore chains of parallel molecules having the same orientation are formed [H20B···O2ⁱ = 2.51 (2) Å, C20—H20B···O2ⁱ = 133 (2)°; symmetry code: (i) -1 + x, y, z].

Experimental

A solution of (4S,4aR)-1-(3-chlorophenyl)-4-phenyl-4a,5-dihydrocyclopenta[c]pyran-3(4H)-one (0.5 g, 1.55 mmol s, 1 equiv.), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in 10 ml anhydrous chloroform (with 0.5–1% ethanol as stabilizer) was refluxed under argon for 1.5 h. The reaction mixture was cooled to 0 °C and the brown precipitate was filtered-off. The filtrate was washed with water and brine, dried with MgSO₄ and the solvent removed in vacuo at 30 °C. The crude product was purified by column chromatography on silica gel (petroleum ether/diethyl ether = 2:1) to afford the major product 1-(3-chlorophenyl)-4-phenylcyclopenta[c]pyran-3(5H)-one (0.094 g, 19%) as a yellow solid, and (Z)-(3-chlorophenyl)(2-ethoxy-5-(hydroxy(phenyl)methylene)cyclopenta-1,3-dien-1-yl)methanone (0.042 g, 8%) as a light brown solid. Crystals suitable for the diffraction experiment were obtained by slow evaporation from solution (pethroleum ether / diethyl ether = 1: 2) of the title compound.