An efficient synthesis of benzyl bromides from aromatic aldehydes using polymethylhydrosiloxane and (bromodimethyl)sulfonium bromide or N-bromosuccinimide

Polymethylhydrosiloxane (PMHS) in combination with (bromodimethyl)sulfonium bromide or NBS has been utilized for the first time for reductive bromination of aromatic aldehydes at room temperature to afford the corresponding benzyl bromides in excellent yields.     

Biological Studies of Some 2,4-Dichloro-5-fluorophenyl Containing Triazolothiadiazoles

Summary. A series of dichlorofluorophenyl containing triazolothiadiazoles were obtained by cyclocondensation of triazole with substituted benzoic, aryloxyacetic, and anilinoacetic acids using POCl₃ as cyclizing agent. The structures of the newly synthesized compounds were characterized and confirmed by IR, ¹H NMR, mass spectra, and elemental analysis. Selected compounds were screened for their antitubercular activity against Mycobacterium tuberculosis. The compound bearing 2,4-dichloro-5-fluorophenyl moiety at position 3, and 6 of the triazolothiadiazole showed excellent activity in vitro primary screening. Compounds with 3-chloro-4-fluorophenyl and 4-fluorophenoxymethyl moieties at position 6 of the triazolothiadiazole showed very good analgesic activity. Triazolothiadiazole with 4-chlorophenyl, 4-fluoro-3-phenoxyphenyl, and 2,4-dichloro-5-fluorophenyl moieties showed excellent antimicrobial activity against the tested strains at 6.25 μg cm⁻³ concentrations.     

Organic reactions in water: an efficient one-pot synthesis of acyloxiranes from Baylis-Hillman adducts using hypervalent iodine

Treatment of Baylis-Hillman adducts with iodosobenzene (PhIO) in the presence of a catalytic amount of KBr in water at room temperature afforded the corresponding acyloxiranes in good yields.     

Synthesis, antiinflammatory and antimicrobial activities of some 2,4-dichloro-5-fluorophenyl substituted arylidenetriazolothiazolidinones

A series of 2,4-dichloro-5-fluorophenyl substituted arylidenetriazolothiazolidinones were obtained by one-pot reaction of 3-(2,4-dichloro-5-fluorophenyl)-4H-1,2,4-triazole-5-thiol with substituted benzaldehydes and monochloroacetic acid in the presence of acetic anhydride, acetic acid, and sodium acetate. The structures of the newly synthesized compounds were characterized and confirmed by IR, ¹H NMR, mass spectra, and elemental analysis. Compounds bearing the 4-methylthiophenyl, 3,4-methylenedioxyphenyl, and 2,3,5-trichlorophenyl moiety showed excellent antiinflammatory activity. The antimicrobial screening studies revealed that compounds with 4-anisyl, 4-methylthiophenyl, 3,4-methylenedioxyphenyl, and 2,3,5-trichlorophenyl at position 5 of the arylidenetriazolothiazolidinone moiety showed excellent activity against all tested strains at 6.25 μg cm⁻³ concentrations.     

Synthesis,antiinflammatory and antimicrobial activities of some 2,4-dichloro-5-fluorophenyl substituted arylidenetriazolothiazolidinones

A series of 2,4-dichloro-5-fluorophenyl substituted arylidenetriazolothiazolidinones were obtained by one-pot reaction of 3-(2,4-dichloro-5-fluorophenyl)-4H-1,2,4-triazole-5-thiol with substituted benzaldehydes and monochloroacetic acid in the presence of acetic anhydride, acetic acid, and sodium acetate. The structures of the newly synthesized compounds were characterized and confirmed by IR, ¹H NMR, mass spectra, and elemental analysis. Compounds bearing the 4-methylthiophenyl, 3,4-methylenedioxyphenyl, and 2,3,5-trichlorophenyl moiety showed excellent antiinflammatory activity. The antimicrobial screening studies revealed that compounds with 4-anisyl, 4-methylthiophenyl, 3,4-methylenedioxyphenyl, and 2,3,5-trichlorophenyl at position 5 of the arylidenetriazolothiazolidinone moiety showed excellent activity against all tested strains at 6.25 μg cm⁻³ concentrations. Correspondence: Mari Sithambaram Karthikeyan, Department of Chemistry, Mangalore University, Mangalagangothri 574199, Karnataka, India.     

The Brauer group of desingularization of moduli spaces of vector bundles over a curve

Let C be an irreducible smooth projective curve, of genus at least two, defined over an algebraically closed field of characteristic zero. For a fixed line bundle L on C, let M _C (r; L) be the coarse moduli space of semistable vector bundles E over C of rank r with ∧ ^r E = L. We show that the Brauer group of any desingularization of M _C (r; L) is trivial.     

Synthesis and Antimicrobial Evaluation of Halogen-Containing Arylidene Thiazolo Triazinediones

A series of 7-substituted arylidene-1,3-thiazolo[2,3-c]-1,2,4-triazine-4,6-diones were synthesized in an one-pot multicomponent reaction of 6-arylmethyl-3-mercapto-1,2,4-triazin-5-ones with substituted benzaldehydes and monochloroacetic acid in the presence of acetic anhydride, acetic acid, and sodium acetate. The structures of the new compounds were supported by IR, ¹H NMR, MS, and analytical data. All the new compounds were tested for their antibacterial and antifungal activity. Arylidene thiazolo triazinediones with 1,3-benzodioxolo substituent at seventh and p-chlorophenyl or 2,4-dichlorophenyl substituents at third displayed good antibacterial and antifungal activity. And also compound bearing 2,3,5-trimethoxyphenyl substituent at seventh and 2,4-dichlorophenyl substituent at third displayed good activity.     

Unramified Brauer group of the moduli spaces of PGL r (ℂ)-bundles over curves

Let X be an irreducible smooth complex projective curve of genus g, with g ≥ 2. Let N be a connected component of the moduli space of semistable principal PGL _r (?)-bundles over X; it is a normal unirational complex projective variety. We prove that the Brauer group of a desingularization of N is trivial.