Microwave Assisted Synthesis of Some Biologically Active Benzothiazolotriazine Derivatives

Journal of Chemistry, Aug 2018

Synthesis of some biologically active benzothiazolotriazine derivatives by microwave irradiation is reported. 2-Amino-6-substituted benzothiazoles 1 on treatment with benzaldehyde in anhydrous ethanol afforded 2-benzylidenoimino-6-substitutedbenzothiazoles 2 which underwent cyclisation with ammoniumthiocyanate in dioxane to give 2-phenyl benzothiazolo [3,2-α]-s-triazine-4-[3H] thiones 3.These both steps were carried out in microwave. Compound 3 with benzoyl chloride in anhydrous pyridine gave 2-phenyl-3-(benzoyl) benzothiazolo [3,2-α]-s-triazine-4-thiones 4 in good yields. The structure of all these compounds have been supported by their elemental analysis and their spectral data. All synthesized compounds were tested for their antibacterial activity using standard drug.

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Microwave Assisted Synthesis of Some Biologically Active Benzothiazolotriazine Derivatives

http://www.e-journals.net 0973-4945 Microwave Assisted Synthesis of Some Biologically Active Benzothiazolotriazine Derivatives PRASHANT KRIPLANI 0 PAWAN SWARNKAR 0 RINKU MAHESHWARI 0 K.G.OJHA 0 0 Department of Pure and Applied Chemistry M. D. S. University Ajmer-305 009(India) Synthesis of some biologically active benzothiazolotriazine derivatives by microwave irradiation is reported. 2-Amino-6-substituted benzothiazoles 1 on treatment with benzaldehyde in anhydrous ethanol afforded 2benzylidenoimino-6-substitutedbenzothiazoles 2 which underwent cyclisation with ammoniumthiocyanate in dioxane to give 2-phenyl benzothiazolo [3,2-α]-striazine-4-[3H] thiones 3.These both steps were carried out in microwave. Compound 3 with benzoyl chloride in anhydrous pyridine gave 2-phenyl-3(benzoyl) benzothiazolo [3,2-α]-s-triazine-4-thiones 4 in good yields. The structure of all these compounds have been supported by their elemental analysis and their spectral data. All synthesized compounds were tested for their antibacterial activity using standard drug. Benzothiazoles; s-triazines; microwave irradiation; antibacterials Introduction Heterocyclic compounds containing nitrogen and sulphur possess potential pharmacological activities1-4. Benzothiazole moiety constitute an important class of heterocyclic compounds possessing diverse type of biological activities viz. antibacterial5, fungicidal6, antituberculotic7,antiallergic8,anticancer9etc.Triazine derivatives are also associated with broad spectrum antibacterial10,antifungal11, antiviral activity12-14 against numerous viruses viz. Rauscher viruses, Leukemia Moloney viruses, Leukemia Rhinovirus type-2,influenza virus type-2,Vaccinia viruses, Vasicular stomatitis and Measules viruses. In view of the activities exhibit by benzothiazoles and triazines, we have reported synthesis of some new benzothiazolotriazine derivatives by conventional method in our earlier paper15.As a part of our continuing interest in biologically active benzothiazolotriazine derivatives, we are reporting a route for synthesis of these compounds by microwave irradiation. Traditional synthesis of compounds suffered from the disadvantages such as long reaction time, low yield and inconvenience of handling. In recent years the use of microwave technology in organic synthesis has received considerable attention. This technology can increase the purity of products, enhance the chemical yield and shorten the reaction time16. All synthesized compounds were tested for their antibacterial activity using standard drug. Experimental All the melting points are uncorrected. The purity of synthesized compounds has been checked by thin layer chromatography. IR spectra are recorded on FT-IR Perkin-Elmer (Spectrum RX1) spectrophotometer(νmax in cm-1) using KBr disc.1H NMR spectra are recorded in CDCl3 on a Bruker DRX-300 MHz using TMS as internal standard. The chemical shifts are reported as parts per million (ppm).Microwave synthesis was carried out in a domestic microwave oven model L.G. MS-194W, 230-50 Hz., 800W. Microwave synthesis of 2-benzylidenoimino-6-substitutedbenzothiazoles 2 A mixture of 2-amino-6-substitutedbenzothiazole 1 (0.001mol) and benzaldehyde (0.001 mol) in minimum quantity of anhydrous ethanol were taken in Erlen Meyer flask capped with a funnel placed in a microwave oven and irradiated at 160 Watt for 1 to 1.5 minutes. The reaction was monitered by silica gel TLC. (Benzene : Acetone 70 : 30).After completion the reaction , the reaction mixture was allowed to attain room temperature and solid separated was filtered. The crude product was recrystallized from redistilled ethanol. Microwave synthesis of 2-phenyl benzothiazolo [3,2-α]-s-triazine-4-[3H] thiones 3 A mixture of 2-benzylidenoimino-6-substitutedbenzothiazole 2 (0.001mol) and ammoniumthiocyanate (0.002mol) were dissolved in minimum quantity of 1,4-dioxane and were taken in Erlen Meyer flask capped with a funnel placed in a microwave oven and irradiated at 160 Watt for 1.5 to 2 minutes. The reaction was monitered by silica gel TLC.(Hexane : DMF 80 : 20).After completion the reaction , the reaction mixture was allowed to attain room temperature and solid separated was filtered. The crude product was recrystallized from redistilled ethanol. Synthesis of 2-phenyl-3-(benzoyl) benzothiazolo [3,2-α]-s-triazine-4-thiones 4 2-Phenyl benzothiazolo [3,2-α]-s-triazine-4-[3H] thiones 3 (0.005mol) was dissolved in minimum quantity of anhydrous pyridine (10ml).To this solution was added benzoyl chloride (0.01mol) dropwise with constant shaking in cold conditions. The reaction mixture was further stirred for 1 hour and poured into acidified icecold water. The solid separated out was filtered and washed repeatedly with water, dried in vacuo and recrystallised from redistilled ethanol. Spectral Analysis of compounds 2a-2d,3a-3d,4a-4d. Compound 2a: M.F.C14H9N2SCl, IR (KBr) ν max in cm-1859(C-Cl),1349(C-S),1597(C=N), 1447,1535(ArC=C), 1HNMR (300MHz, (...truncated)


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Prashant Kriplani, Pawan Swarnkar, Rinku Maheshwari, K. G. Ojha. Microwave Assisted Synthesis of Some Biologically Active Benzothiazolotriazine Derivatives, Journal of Chemistry, 3, DOI: 10.1155/2006/486723