H 2SO 4-Silica efficiently catalyzes the three-component condensation reaction of aldehydes, 1,3-dicarbonyl compounds and urea/thiourea under solvent free conditions to afford the corresponding dihydropyrimidinones and thio-derivatives in high yields. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of giving good yields and requiring short reaction times.
A rapid and efficient method for the transthioacetalization of acylals (1,1-diacetates) and acyclic and cyclic acetals is described. The reaction was carried out using 1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane tribromide (1 mol%). The yield of the transthioacetalization was high and reaction conditions involve the use of acetonitrile as the solvent at room temperature; isolation is simple and the products are nearly pure.
Antimony trichloride(SbCl3) was demonstrated to be an effective catalyst for the cyanosilylation of a wide variety of carbonyl compounds under solvent-free conditions. The reactions proceeded smoothly at room temperature to afford the corresponding cyanosilylethers in good to excellent yields.
Benzyl DABCO bromide was found to be an efficient and mild reagent for the reduction of sulfoxides to the corresponding sulfide using sulfuric acid adsorbed silica gel under solvent-free conditions at room temperature.
Benzyl triethyl ammonium tribromide was prepared by oxidation of bromide ion with HNO3. The resulted tribromide was used as an efficient, regioselective, and recoverable reagent for the bromination of anilines, phenols and anisoles in good to excellent yields at room temperature.
Stable crystalline 1-Benzyl-4-aza-1-azonia-bicyclo[2.2.2]octane tribromide (BABOT), can be readily synthesized from the reaction of the corresponding bromide with HNO3 and aqueous KBr. Selective Oxidation of a variety of dialkyl and alkyl Aryl sulfides to the corresponding sulfoxides in high yield was achieved by this reagent in solution (CH3CN/H2O) and solvent free conditions. The reaction proceeds under neutral and mild conditions and can be carried out easily at room temperature with regeneration of BABOT. In this method purification of products is straightforward and no over oxidation to sulfone was noted.
AUTHOR KEYWORDS: 1-Benzyl-4-aza-1-azonia-bicyclo[2. 2.2]octane tribromide; Oxidation; Solvent free; Sulfide; Sulfoxide INDEX KEYWORDS: Solvents; Sulfur compounds, 1-Benzyl-4-aza-1-azonia-bicyclo[2. 2.2]octane tribromide; Environmentally benign synthesis; Oxidation of sulfides; Selective oxidation; Solvent free; Solvent free conditions; Sulfide; Sulfoxide, Oxidation PUBLISHER: Korean Chemical Society
Damghan University strives to be one of the top and outstanding universities in terms of scientific developments both theoretically and practically. Damghan University will have a transformative impact on society through innovation in education, research and entrepreneurship.