(2E)-1-[2-Hydr­oxy-4-(2-methyl­prop­oxy)phen­yl]-3-(4-methyl­phen­yl)prop-2-en-1-one

Jeshal G Maheta; Vijay M Barot; Mukesh M Jotani; Edward R T Tiekink

doi:10.1107/S1600536810010809

. 2010 Mar 27;66(Pt 4):o942–o943. doi: 10.1107/S1600536810010809

(2E)-1-[2-Hydroxy-4-(2-methylpropoxy)phenyl]-3-(4-methylphenyl)prop-2-en-1-one

Jeshal G Maheta ^a, Vijay M Barot ^a, Mukesh M Jotani ^b,^‡, Edward R T Tiekink ^c,^*

PMCID: PMC2983789 PMID: 21580748

Abstract

The benzene rings in the title compound, C₂₀H₂₂O₃, form a dihedral angle of 10.39 (8)°. Overall, the molecule is approximately planar with the exception of one of the terminal methyl groups; excluding this group, the r.m.s. deviation for the remaining 22 non-H atoms is 0.0968 Å. The conformation about the C=C bond is E, and an intramolecular O—H⋯O hydrogen bond leads to the formation of an S(6) motif. In the crystal, linear supramolecular chains are formed along the a axis via C—H⋯O contacts, and these are connected into double chains via C—H⋯π interactions.

Related literature

For the use of α,β-unsaturated ketones in organic synthesis, see: Marzinzik & Felder (1998 ▶); Srikanth et al. (2005 ▶); Nehad et al. (2007 ▶); Gaede & Mcdermott (1993 ▶); Shibata et al. (1993 ▶); Xu et al. (2001 ▶). For the biological activity of α,β-unsaturated ketones, see: Prasad et al. (2008 ▶); Zhao et al. (2007 ▶). Lambert et al. (2009 ▶); Jung et al. (2008 ▶); Reichwald et al. (2008 ▶); Boumendjel et al. (2008 ▶); Domínguez et al. (2005 ▶); Yun et al. (2006 ▶). For semi-empirical quantum chemical calculations, see: Stewart (2009 ▶).

Experimental

Crystal data

C₂₀H₂₂O₃
M _r = 310.38
Triclinic,
a = 6.7795 (8) Å
b = 9.8830 (12) Å
c = 13.9064 (17) Å
α = 74.740 (2)°
β = 78.857 (2)°
γ = 74.103 (2)°
V = 857.12 (18) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.20 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.932, T _max = 0.991
9290 measured reflections
3530 independent reflections
2452 reflections with I > 2σ(I)
R _int = 0.019

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.142
S = 1.03
3530 reflections
212 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810010809/pk2236sup1.cif

e-66-0o942-sup1.cif^{(19.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810010809/pk2236Isup2.hkl

e-66-0o942-Isup2.hkl^{(169.6KB, hkl)}

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

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

Cg is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2o⋯O1	0.82	1.77	2.499 (2)	148
C12—H12⋯O2ⁱ	0.93	2.55	3.268 (2)	135
C17—H17b⋯Cgⁱⁱ	0.97	2.82	3.705 (2)	153

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

Acknowledgments

The authors are grateful to the Department of Science and Technology (DST) and the SAIF, II Madras, India, for the X-ray data collection.

supplementary crystallographic information

Comment

α,β-Unsaturated ketones (chalcones) are useful key intermediates in organic synthesis (Marzinzik & Felder, 1998; Srikanth et al., 2005). For example, they attract interest owing to their utility as starting materials in the synthesis of the five- (Nehad et al., 2007 & Gaede & Mcdermott, 1993), six- (Shibata et al., 1993), and seven-membered (Xu et al., 2001) heterocycles. Several analogues have been demonstrated to be active against both gram-positive and gram-negative bacterial strains, and also against fungal strains (Prasad et al., 2008; Zhao et al., 2007). Moreover, chalcones possess a wide spectrum of biological activities such as anti-oxidant, neuroprotective, anti-leishmanial, anti-mitotic, anti-malarial, anti-cancer, etc. (Lambert et al., 2009; Jung et al., 2008; Reichwald et al., 2008; Boumendjel et al., 2008; Domínguez et al., 200; Yun et al., 2006). In view of the importance of these compounds, the crystal structure of title compound, (I), was determined.

With the exception of the methyl-C19 atom, the molecular structure, Fig. 1, is essentially planar. Thus, the r.m.s. deviations of the 22 non-H atoms is 0.0968 Å [maximum deviation = 0.2173 (15) Å for the C6 atom] with the C19 atom lying 1.313 (4) Å out of this plane. The near planarity is manifested in the torsion angles with the maximum deviations from linearity (excluding that involving the C19 atom; O3–C17–C18–C19 = -58.7 (2) °) found in the C8–C9–C10–O1 and C8–C9–C10–C11 torsion angles of -6.2 (2) and 173.89 (14) °, respectively. The dihedral angle formed between the benzene rings is 10.39 (8) °. The conformation about the C8═C9 bond [1.325 (2) Å] is E. The presence of an intramolecular O–H···O_carbonyl hydrogen bond is noted, Table 1, which closes an S(6) motif.

In the crystal packing, both C–H···O and C–H···π interactions are observed. Linear supramolecular chains aligned along the a axis are mediated by C–H···O contacts, Fig. 2 and Table 1. Centrosymmetrically related pairs of these chains are connected into a double chain via C–H···π contacts formed between the methylene-C17—H and the ring centroid of the tolyl ring, Fig. 3 and Table 1.

Semi-empirical Quantum Chemical Calculations were performed on (I) using the MOPAC2009 program (Stewart, 2009) to optimize the structure with the Parameterization Model 6 (PM6) approximation together with the restricted Hartree-Fock closed-shell wavefunction. Minimizations were terminated at an r.m.s. gradient of less than 0.01 kJ mol-1 Å^-1. The geometry optimised structure displays a significant difference in the relative orientation of the tolyl ring compared with the experimental structure. This is quantified by the value of the C6—C5—C8—C9 torsion angle of 150.7 compared with the experimental value of 179.72 (15) °. This change is related to the participation of this ring in the C–H···π contact as discussed above.

Experimental

A mixture of 2-hydroxy-4-isobutoxy acetophenone (0.01 mol) and 4-methyl benzaldehyde (0.01 mol) in ethanol (40 ml) were placed in a 250 ml round bottom flask and the resulting solution stirred at room temperature. After the solution became clear, a solution of potassium hydroxide (40%, 40 ml) was added slowly with constant stirring followed by stirring at room temperature for a further 20 h. After the completion of reaction, as indicated by TLC, the contents were poured onto crushed ice and acidified with dilute HCl (10%). The solid separated and was washed with water, filtered, and the crude product was crystallized from methanol to obtain (I) in 90 % yield; m.pt. 417 K. The yellow needles were obtained by the slow evaporation of a methanol solution of (I).