v NaOH in water, EPZ015938 solubility dmso reflux for 3 h. vi 7-Aca, HCHO, Et3N in THF, rt, for 4 h. vii 6-Apa, HCHO, Et3N in THF, rt, for 4 h. vii 4-Chlorophenacylbromide in absolute LY2603618 ic50 ethanol, dried sodium acetate, reflux for 12 h Scheme 3 i 3-Hydroxy-4-phenoxybenzaldehyde,

pyridine-4-carbaldehyde, 2-hydroxybenzaldehyde in absolute ethanol, irradiation by MW at 200 W, 140 °C for 30 min. ii CS2 and KOH in ethanol, reflux for 13 h. iii 7-Aca, HCHO, Et3N in THF, rt, for 4 h. iv 6-Apa, HCHO, Et3N in THF, rt, for 4 h Ethyl 4-(4-amino-2-fluorophenyl)piperazine-1-carboxylate (3), that was obtained starting from compound 1 by two steps, was converted to the corresponding arylmethylenamino derivatives (4a–f) by the treatment with several aromatic aldehydes. In the FT-IR and 1H NMR spectra of these compounds, no signal pointing the –NH2 group was seen. Instead, additional signals derived from aldehyde moiety were recorded at the related chemical shift values in the 1H NMR spectra. The cyclocondensation of compound 5, that was obtained from the reaction

of 4 with benzylisocyanate, with ethyl bromoacetate or 4-chlorophenacyl Romidepsin nmr bromide produced the corresponding hybrid molecules incorporating a 4-oxo-1,3-oxazolidine (6) or 4-chlorophenyl)-1,3-oxazole (7) nucleus in the 2-fluorophenylpiperazine-1-carboxylate skeleton. The 1H and 13C NMR spectra of compound 7 exhibited additional signals at aromatic region originated from 4-chlorophenyl nucleus as a result of condensation. Moreover, the elemental analyses and mass spectral data of derivatives 6 and 7 were compatible with the suggested structures. The treatment of compound 3 with ethyl bromoacetate at room temperature in the presence of triethylamine resulted in the formation of compound 8. When compound 8 was converted to the corresponding hydrazide (9) by refluxing with hydrazine hydrate, the signals originated from ester function was disappeared in the 1H and 13C Meloxicam NMR spectra. Instead, new signals due to –NHNH2 protons were

seen at 5.93 and 9.09 ppm. Meanwhile, the stretching frequency band of this group was recorded at 3,313 cm−1 as a wide signal characteristic for the hydrazide structure. Compounds 6 and 7 gave mass fragmentation confirming the proposed structures. The synthesis of compounds 10 and 11 was carried out by the treatment of compound 7 with the corresponding isothiocanates. These compounds displayed spectroscopic data and elemental analysis results consistent with the assigned structures. The intramolecular cyclization of compound 10 generated the corresponding 1,3,4-thiazole compound (12) in acidic media. On the other hand, the basic treatment of compounds 10 and 11 caused to the cyclization of the (arylamino)carbonothioylhydrazino side change leading to the formation of 5-thioxo-4,5-dihydro-1H-1,2,4-triazol derivatives (13 and 14). With the conversion of compounds 10 and 11 to compounds 12–14, two of NH signals were disappeared in the 1H NMR spectra.