Synthesis and Characterization of Novel 2-(1,2,3-Triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles and 2-(4,5-Dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles

Reactions of 1-(5-methyl)-1H-1,2,3-triazol-4-yl)ethan-1-ones and benzaldehydes in ethanol under basic conditions gave the corresponding chalcones. Reactions of the chalcones combined with thiosemicarbazide in dry ethanol containing sodium hydroxide afforded the corresponding pyrazolin-N-thioamides. Reactions of the synthesized pyrazolin-N-thioamides and several ketones (namely, ethyl 2-chloro-3-oxobutanoate, 2-bromoacetylbenzofuran, and hydrazonoyl chloride) gave the corresponding novel 2-(1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles in high yields (77–90%). Additionally, 2-(4,5-dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles were obtained in high yields (84–87%) from reactions with N-pyrazoline-thioamides and 4-bromoacetyl-1,2,3-triazoles under basic conditions. The structures of six of the newly synthesized heterocycles were confirmed by X-ray crystallography.

Recent synthetic methods used to produce pyrazoles involve, for example, the cycloaddition of N-isocyanoiminotriphenylphosphorane in the presence of silver carbonate [16], oxidative condensations of carbonyl compounds (aldehydes and ketones) and hydrazine monohydrochloride [17], oxidative cyclization of β,γ-unsaturated hydrazones [18], and the reaction of enaminones and hydrazines in the presence of iodine as a catalyst [19]. For the production of thiazoles, the most recent synthetic procedures involve reactions of aldehydes
The 1 H NMR spectrum of compound 8 showed two characteristic double doublets (J = 4.8 Hz) that appeared at 3.37 and 4.42 ppm, corresponding to the CH 2 protons of the pyrazolinyl moiety. In addition, it showed a double doublet (J = 4.8 and 16.4 Hz) that appeared at 5.70 ppm corresponding to the pyrazolinyl proton at position 5. The 13 C NMR spectrum of 8 showed two high-field signals at 162.3 and 165.3 ppm that correspond to the carbonyl carbon and C2 of the thiazolyl moiety, respectively. For compound 9, the pyrazoline protons appeared as three double doublets of one proton each at 3.43 (J = 6.2 and 18.1 Hz), 4.18 (J = 11.9 and 18.1 Hz), and 5.68 (J = 6.2 and 11.9 Hz). The 13 C NMR spectra of 9 and 10 showed the coupling between the fluorine atoms and the carbons (C2-C6) of the aryl rings. appeared at 5.70 ppm corresponding to the pyrazolinyl proton at position 5. The 13 C NMR spectrum of 8 showed two high-field signals at 162.3 and 165.3 ppm that correspond to the carbonyl carbon and C2 of the thiazolyl moiety, respectively. For compound 9, the pyrazoline protons appeared as three double doublets of one proton each at 3.43 (J = 6.2 and 18.1 Hz), 4.18 (J = 11.9 and 18.1 Hz), and 5.68 (J = 6.2 and 11.9 Hz). The 13 C NMR spectra of 9 and 10 showed the coupling between the fluorine atoms and the carbons (C2-C6) of the aryl rings.       C12 deviating from the least squares planes of the rest of the atoms by 0.324(3)Å for the first molecule and C40 deviating by 0.271(3)Å for the second molecule.

Synthesis of Chalcones 3a,b
A mixture of 1a or 1b (12 mmol) and 2a or 2b (12 mmol) in EtOH (50 mL) was added slowly to a solution of NaOH (0.5 g, 12.2 mmol) in water (10 mL). The mixture was stirred at 25 • C for 4 h and the solid obtained was filtrated, washed with cold water, dried, and recrystallized from EtOH to give pure 3a or 3b.  [36]). The spectroscopic data of 3b agreed with those reported.

Synthesis of Compounds 8-10
To a suspension of 4a or 4b (2 mmol) in EtOH (15 mL) and Et 3 N (0.2 mL, 5 (0.16 g, 1 mmol), 6 (0.24 g, 1 mmol) or 7 (0.22 g, 1 mmol) was added. The mixture was heated under reflux for 2 h and the solid obtained on cooling was collected by suction filtration, washed with EtOH, and recrystallized from DMF to give the corresponding heterocycle 8, 9, or 10, respectively. reflux for 2 h and the solid obtained on cooling was collected by filtration, washed with EtOH, and recrystallized from DMF to give the corresponding compound 13-15.
The crystal structures have been deposited in the Cambridge Structural Database under reference CCDC Numbers 2220613-2220618.