Synthesis , Characterization and Antimicrobial Evaluation of New Chalcone Derivatives From 3-benzyloxy-4-methoxybenzaldehyde

A series of chalcone derivatives (2a–i) were prepared via the reaction of 3-benzyloxy-4methoxybenzaldehyde with the appropriately acetophenon derivatives. The structures of all the newchalcone derivatives (2a–i) synthesized in this study were established on the basis of 1H NMR and 13C NMR spectral data, and elemental analyses The antibacterial activitie of the synthesized compounds (2ai) was carried out by well diffusion and MIC method.

Pharmacological properties of chalcones are due to the presence of both á,â, unsaturation 18 and an aromatic ring.Constant interest in chalcones has resulted in syntheses of new derivatives using both classical [19][20] and combinatorial techniques 21 .
In this study, a series of new chalcone-like compound (2a-i) were synthesized by the reaction of 3-benzyloxy-4-methoxybenzaldehyde with the appropriately acetophenon derivatives.The structures of all the chalcone derivatives (2a-i) synthesized in this study were established on the basis of 1 H NMR and 13 C NMR spectral data, and elemental analyses.The structure of compound 2i was further confirmed by X-ray analysis of single crystal.

RESULTS AND DISCUSSION
Melting points of the compound were measured using an Electrothermal 9100 apparatus.IR spectrums (KBr or liquid) were taken by a Jasco FT=IR-430 IR spectrophotometer. 1 H and 13 C NMR spectra were recorded using a BruckerAvance III instrument using tetramethylsilane (TMS, d 0.00) for 1 H NMR and DMSO for 13 C NMR spectroscopy as internal reference standards; J values were given in hertz.The multiplicities of the signals in the 1 H NMR spectra are abbreviated by s (singlet), d (doublet), t (triplet), q (quarted), m (multiplet),

Reagent
3-benzyloxy-4-methoxybenzaldehyde and appropriately acetophenon derivatives were commercial products with the highest reagent grade.

Chemistry
To a mixture of 3-(benzyloxy)-4methoxybenzaldehyde (2g, 0.008 mol) and appropriately acetophenon derivatives (0.008 mol) in éthanol 20 ml in the presence of a catalytic amount of sodium hydroxide solution (5 ml) was added slowly with stirring (6 h), neutralized with HCl solution (10%) the contents of the flask were poured into ice cold water (500 ml) and left to stand for 5 h,the organic layer was dried over anhydrous Na 2 SO 4 ,(Scheme 1)The resulting crude solid was filtered and purified by recrystallization in ethanol.The structure of the compound 9(2i) was further confirmed by X-ray analysis of single crystal.Crystal suitable for x-ray analysis was grown by slow evaporation of a mixture acetone/ ethanol solution at room temperature.The crystal used for data Collection was of the dimension) 0.51 x 0.31x0.15mm(

X-ray analysis
The compound, 2i( C 23 H 19 ClO 3 ), exists in an E conformation with respect to the C=C bond.The central benzene ring forms a dihedral angle of 88.96 (2)° with the chlorobenzene ring and a dihedral angle of 22.53 (2)° with the terminal benzene ring.No significant intermolecular interactions are observed (fig1, fig2).

Refinement
All H atoms were localized in Fourier maps but introduced in calculated positions and treated as riding on their parent C atoms with C-H = 0.95Å to 0.99Å and Uiso(H) = 1.2 or 1.5Ueq(C).
Crystallographic data and details of the data collection and structure solution and refinements are listed in