Zinc Oxide as a New, Highly Efficient, Green, and Reusable Catalyst for Microwave-Assisted Michael Addition of Sulfonamides to α,β-Unsaturated Esters in Ionic Liquids.
An efficient procedure for the synthesis of carboacyclic nucleosides via microwave-assisted Michael addition of pyrimidine and purine nucleobases to α,β-unsaturated esters in the presence of catalytic amounts of zinc oxide (ZnO) and tetrabutylammonium bromide (TBAB) is described. The reactions proceed rapidly in good to excellent yields.Key words: ZnO–TBAB, green chemistry, Michael addition, nucleobase, solvent-free, microwave.
A simple, clean, and efficient procedure for the green synthesis of some N-alkyl derivatives of sulfonamides is described. Microwave-assisted Michael addition of sulfonamides to α,β-unsaturated esters, in the presence of catalytic amount of zinc oxide (ZnO) in 1-butyl-3-methylimidazolium bromide ([bmim]Br), affords the title compounds in high yields and short reaction times.Key words: zinc oxide, green chemistry, microwave, Michael addition, sulfonamide, ionic liquid.
AbstractA series of amino-acid based ionic liquids (Bmim[AA]s) have been synthesized and evaluated as catalysts, in aqueous solution. The results of a kinetic study of the thiol-Michael reaction of L-Cysteine with trans-β-nitrostyrene demonstrated the advantages of using (Bmim[AA]s) as organocatalysts. The benefits include high rate constants; mild reaction conditions; and, a reusable catalyst, which leads to a simple and efficient method for these important kinds of reactions.
Here, we have demonstrated regioselective synthesis of novel 2-alkoxy-3-arylimidazo[1,2-a]pyridines using nano-NiFe2O4 as reusable catalyst via one-pot sequential aza-Michael addition, Fe-promoted ligand transfer and C–H imination reactions.
Organic reactions in ionic liquids: MgO as efficient and reusable catalyst for the Michael addition of sulfonamides to α,β-unsaturated esters under microwave irradiation