One-Pot Synthesis and Fungicidal Activities of Derivatives of Imidazo [2,1-b]-1,3,4-thiadiazol-5(6H)-one

The isothiocyanates 2, obtained from aza-Wittig reactions of vinyliminophosphoranes 1 with CS ₂ , reacted with hydrazine to give 3-amino-2-thioxo-4-imidazolidinones 4. One-pot reactions of 4, aromatic isocyanates, Ph ₃ P, C ₂ Cl ₆ , and Et ₃ N generated imidazo[2,1-b]-1,3,4-thiadiazol-5(6H)-ones 7. Compound 7 exhibited good fungicidal activities, especially against Sclerotinia sclerotiorum de Bary and Botrytis Cinerea Pers.     

The Synthesis of Amino Acid Methyl Ester 5′-Phosphoamidates of Protected Uridine

In this article, we used the Atherton–Todd reaction to synthesize amino acid methyl ester 5′-phosphoamidates of uridine as prodrugs. Their structures were confirmed by ¹H NMR, ³¹P NMR, ¹³C NMR, IR, and mass spectrometry.

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Synthesis and Antibacterial Studies of Some Novel 2-(Coumarin-3-yl)-5-mercapto-1,3,4-oxadiazoles Containing 2,4,6-Trisubstituted s-Triazine Derivatives

A new series of 2-(coumarin-3-yl)-5-mercapto-1,3,4-oxadiazoles based on various aryl thiourea/ureas incorporating a 1,3,5-s-triazine moiety is reported. The components of this series have been obtained by the reaction of cyanuric chloride (1) with 2-(coumarin-3-yl)-5-mercapto-1,3,4-oxadiazole (2). The prepared 2-{(coumarin-3-yl-1,3,4-oxadiazolyl)-5-thio}-4,6-dichloro-s-triazine (3) was subsequently treated with morpholine (4) to form 2-{(coumarin-3-yl-1,3,4-oxadiazolyl)-5-thio}-4-(morpholino)-6-chloro-s-triazine (5). This was further treated with various substituted aryl urea/thioureas (6a–k/7a–k) to afford the title compounds 8a–k and 9a–k, which were and tested for their antibacterial activity (MIC) against different microorganisms. The structures of the novel synthesized compound have been established on the basis of ¹H NMR and FT-IR data together with elemental analysis.

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Synthesis of some novel 5-substituted benzamido-6-arylamino-pyrazolo[3,4-D]pyrimidin-4-one derivatives for herbicidal activity

Abstract

Sixteen novel 3-methylthio-5-substituted benzamido-6-arylamino-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H)-one derivatives (4a–p) were successfully synthesized from iminophosphoranes, aryl isocyanate, and substituted benzoylhydrazine. The structures of the title compounds were elucidated by FT-IR, ¹H NMR, ¹³C NMR, and HRMS. Herbicidal activity of the compounds 4a–p against Brassica napus (rape), Echinochloa crusgalli (barnyard grass), Cucumis sativus (cucumber), and Triticum aestivum (wheat) were determined. The results showed that 5-(2-chlorobenzamido)-6-phenylamino-3-methylthio-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H)-one (4c) displayed remarkable inhibition activity against the stalk and root of rape with 100% inhibition rate at the dosages of 10?mg/L and 100?mg/L, and 5-(4-nitrobenzamido)-6-phenylamino-3-methylthio-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H) -one (4d) exhibited excellent activity against the stalk and root of barnyard grass with 100% inhibition rate at the same dosages.     

Synthesis in Water and Antimicrobial Activity of 5-Trichloromethyl-4,5-dihydroisoxazoles

Two series of 5-trichloromethylisoxazoles were synthesized from the cyclocondensation of 1,1,1-trichloro-4-methoxy-3-alken-2-ones [Cl₃CC(O)C(R²) = C(R¹)OMe, where R¹ = H, Me, Et, Pr, iso-Pr, cyclo-Pr, Bu, terc-Bu, CH₂Br, CHBr₂, CH(Me)SMe, (CH₂)₂Ph, and Ph, and R² = H; R¹ = H and R² = Me and Et; R¹ and R² = -(CH₂)₄- and -(CH₂)₅-; and R¹ = Et and Ph and R² = Me] with hydroxylamine hydrochloride through a rapid one-pot reaction in water. The 5-trichloromethyl-4,5-dihydroisoxazoles were aromatized by reaction with concentrated sulfuric acid to obtain the respective 5-trichloromethylisoxazoles. Their structures were confirmed by elemental analysis, ¹H/¹³C nuclear magnetic resonance, and electron impact mass spectroscopy. Crystal structure analysis for 5-triclhoromethyl-5-hydroxy-3-propyl-4,5-dihydroisoxazole (2d) and 5-trichloromethyl-5-hydroxy-3,4-hexamethylene-4,5-dihydroisoxazole (2o) is presented. The antimicrobial activities of the 5-trichloromethyl-4,5-dihydroisoxazole derivatives were examined using the standard twofold dilution method against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and yeasts (Candida spp. and Cryptococcus neoformans). All of the tested 5-trichloromethyldihydroisoxazoles exhibited antibacterial and antifungal activities at the tested concentrations.

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Atom-Economic Route to Densely Functionalized Thiophenes via Base-Catalyzed Rearrangement of 5-Propargyl-2H-thiopyran-4(3H)-ones

An atom-economic route to densely functionalized thiophenes has been developed via base-catalyzed rearrangement of 5-propargyl-2H-thiopyran-4(3H)-ones involving tandem retro-thio Michael addition, propargyl isomerization, and intramolecular thio-addition to allenes.     

P2O5-Promoted Efficient and Diastereoselective Synthesis of Substituted 5-Methylene-dihydropyran-2,6-diones and 3-Methylene-3,4-dihydropyran-2-ones

A simple, efficient, and diastereoselective synthesis of 5-methylene-dihydropyran-2,6-diones and 3-methylene-3,4-dihydropyran-2-ones from substrates afforded by the S_N2 reaction between the acetyl derivatives of the Baylis–Hillman adducts and methylacetoacetate or acetylacetone or benzoyl acetone via saponification followed by P₂O₅-mediated cyclization is described.     

Synthesis of Tri- and Disalicylaldehydes and Their Chiral Schiff Base Compounds

A suitable procedure for convenient preparation of 1,3,5-tris(4-hydroxy-5-formylphenyl)benzene (6) was exploited via 5-bromosalicylaldehyde as starting reactant. Among the obtained products, compound 6, 4-methoxy-3-formylphenylboronic acid (9), 1,3,5-tris(4-methoxy-5-formylphenyl)benzene (10), and 4-methoxy-4′-hydroxyl-3,3′-diformyl-1,1′-diphenyl (11) had not been reported previously. Two new chiral Schiff base ligands, L1 and L2, were obtained from the tri- or disalicylaldehydes.