Showing papers in "Letters in Organic Chemistry in 2014"

Recent Advances on the Synthesis of Chalcones with Antimicrobial Activities: A Brief Review

Abstract: The increasing resistance of bacteria and fungi to antimicrobial drugs has been a matter of concern in public health in the last decades. The continuing need for novel therapeutic compounds is still urgent regarding the number of new diseases and resistant strains of microorganisms. Chalcones are ketones , -unsaturated with one aromatic ring bonded to carbonyl and another aromatic ring bonded to an olefin function. Literature has already reported the antimicrobial potential of several chalcones against a wide range of fungal and bacterial strains, including resistant ones; clearly indicating that they are attractive target compounds for new antimicrobial drug development. Several studies have shown that the introduction of different functional groups is a strategy used to improve the biological activity of these compounds, moreover, the structure of chalcones can also be employed as an intermediate reaction, enabling different reactions and giving rise to new molecules. In this review, we describe recent advances on the synthesis of chalcones with antimicrobial activities.

Stabilization of radicals by imides. A modular stereoselective approach to protected functional 1,2-diamines.

Abstract: Radical addition of various xanthates to N,N'-diacylimidazol-2-one occurs readily to give protected 1,2-diamines. The imide group stabilizes the adduct radical sufficiently to enable a second addition to unactivated alkenes. In some cases, the addition product could be converted into an indoline, a tetralone, or further added to an indole. Regioselective removal of one acyl group could also be accomplished.

Synthesis of 3-substituted Coumarins: An Efficient Green Approach Using L-proline as Catalyst in Triethanolamine Medium

Abstract: The title compounds (III) are efficiently obtained by Knoevenagel condensation of salicylaldehydes (I) with active methylene compounds (II) under green reaction conditions.

An eco-friendly n-formylation of amines using nano cerium oxide asa recyclable catalyst under solvent-free and ultrasound irradiationconditions at room temperature

Abstract: A new method for the synthesis of formamides has been developed by the N-formylation of amines with formic acid in the presence of nano cerium oxide as an efficient and recyclable catalyst under ultrasound irradiation. The reaction system is remarkably simple and environmentally benign.

Synthesis, Characterization and Antibacterial Activity of Cyclic Sulfamide Linked to Tetrathiafulvalene (TTF)

Abstract: We herein describe the synthesis and antibacterial activity of cyclic sulfamide linked to tetrathiafulvalene (TTF). This approach exploits the inherent chemistry of biomolecules and �-donors compounds to generate symmetric bis-trimethyltetrathiafulvalenyl-2-thiophenyl cyclic sulfamides. Two strategies are revealed, one centres on the Ring- closing olefin metathesis using the Grubbs catalyst a second strategy based on the direct alkylation of dibromoalkane de- rivatives with symmetric sulfamide under basic conditions. All the newly synthesized compounds were screened for their antimicrobial activities and some of them were found to possess good or moderate antimicrobial activity.

Niobium Pentachloride Catalyzed One-Pot Multicomponent Condensation Reaction of β-Naphthol, Aryl Aldehydes and Cyclic 1, 3-Dicarbonyl Compounds

Abstract: as a new, mild and efficient method for the synthesis of xanthene derivatives (29 examples)

Synthesis of Novel 2-(Methylthio)benzo[g][1,2,4]triazolo[1,5-a]quinazolin- 5-(4H)-one and its Derivatives

Abstract: A novel 2-(methylthio)benzo(g)(1,2,4)triazolo(1,5-a)quinazolin-5(4H)-one was synthesized employing di- methyl N-cyanoimidodithiocarbonate and 3-hydrazinyl-2-naphthoic acid as building blocks. Chemical transformation of the inherent lactam group in the target molecule provided access to a variety of heterocylic derivatives. The obtained compounds are characterized and confirmed by NMR, IR, and HREI-MS analyses.

An Efficient and Selective Pd-catalyzed Dehalogenation Reaction

Abstract: An efficient, simple, practical and selective Pd-catalyzed method for the dehalogenation of a variety of 3-halo-2(5H)-furanones (27 examples) using N,N-diisopropylethylamine as both hydrogen source and base.