Background: Thiazoles and pyridines are versatile synthetic scaffolds possessing wide spectrum of biological effects including potential antimicrobial activity. Objective: In the efforts to develop suitable antimicrobia drugs, medicinal chemists have focused on thiazole derivatives. A novel series of 2-thiazolyl pyridines was prepared in a one-pot three-component reaction using 2-bromoacetyl pyridine as a starting precursor. Method: Structure of the synthesized compounds was elucidated by spectral data (FT-IR, 1H NMR, 13C NMR, and mass) and elemental analyses. The prepared compounds were screened for their in vitro antimicrobial activity. Results: The results revealed that compounds 4a,b,e-g and 12 showed promising activity. Molecular docking studies using MOE software were carried out for compounds 4a and 4b which exhibited potent activities indicated by the diameter zones (4a; 3.6, 4.0, 1.2 mm) (4b; 4.2, 3.5, 1.5 mm) and the binding affinities (4a; -5.7731, -5.3576, -4.6844 kcal mol-1) (4b; -5.9356, -2.8250, -5.3628 kcal mol-1) against Candida albicans, Bacillus subtilis and Escherichia coli, respectively. Conclusion: This paper describes a facile and efficient MCR for synthesis of 2-thiazolyl pyridines from reaction of 2-bromoacetyl pyridine with different reagents. There was an agreement between the values of binding affinities and interactions and the data obtained from the practical antimicrobial screening of the tested compounds.

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I N THIS work, 5 thiazolidinone derivatives of the type 5-benzylidene -2-(1-piperidinyl)- (105) are synthesized and characterized using conventional tools analyses. They are tested as antioxidants for local base stock and the efficiency of these compounds, as antioxidants, was monitored through studying the change in total acid number and viscosity, the results reveal that the efficiency order is ranked as follows 105 < 104 < 103 <102 < 101. The quantum chemical parameters such as the lowest unoccupied molecular orbital (LUMO), the highest occupied molecular orbital (HOMO) energy levels and the energy gap (E HOMO -E LUMO ) were calculated. The experimental results were on the same line with the quantum chemical calculations.

EXPERIMENTALMelting points were measured on an Electrothermal IA 9000 series digital melting point apparatus. IR spectra were recorded in potassium bromide discs on Pye Unicam SP 3300 and Shimadzu FTIR 8101 PC infrared spectrophotometers. NMR spectra were recorded on a Varian Mercury VX-300 NMR spectrometer operating at 300 MHz ( 1 H NMR) or 75 MHz ( 13 C NMR) and run in deuterated dimethylsulfoxide (DMSO-d6). Chemical shifts were related to that of the solvent. Mass spectra were recorded on a Shimadzu GC-MS-QP1000 EX mass spectrometer at 70 eV. Elemental analyzes were measured by using a German made Elementar vario LIII CHNS analyzer. Hydrazonoyl halides were prepared as previously reported in the respective literature [45]. Synthesisof [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines 5a-e and [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines 7a-d: General method. A mixture of aminomercaptotriazole 1 (0.144g, 1 mmol) and the appropriate hydrazonoyl halides 2(3) (1 mmol of each) in dioxane (20 mL) containing triethylamine (0.1 g, 1 mmol) was refluxed for 4-8 h. (monitored by TLC). The formed precipitate was isolated by filtration, washed with methanol, dried and recrystallized from the proper solvent to give the respective triazolothiadiazines 5a-e and triazolotetrazines 7a-d. 3-Ethyl-6-methyl-7-(2-phenylhydrazono)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (5a). Yellow

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