Mannich-type reactions with aliphatic and aromatic substrates were performed using a variety of protic ionic liquids.(PILs). The work was conducted under solvent-free conditions to avoid the use of organic solvents and traditional catalysts by using ILs as dual catalyst and solvent. PILs were synthesized by reaction of different imidazoles with sultones followed by protonation of these zwitterions with organic and inorganic acids with variable pKa values. The synthesized ILs were tested for their catalytic activity with Mannich reaction using cyclohexanone, acetophenone, indole and aminophenol as Mannich substrates. Pharmaceutically important molecules, such as tropinone, tropane and tropine alkaloids, were also synthesized. Reactions conditions have been optimized by investigating the effects of temperature, solvents, counter-ions, acidity and amount of ILs. Among the synthesized   imidazolium based PILs, 1-methylimidazolium-3-(3-propylsulfonicacid) cation with camphorsulfonate anion gave better results in comparison with the rest. This work uses a mild and solvent-free reaction conditions, easy work up procedure and high yields of products in short time. It can be potentially contribute significantly to organic synthesis.

Mannich reactions catalyzed by sulfonate for the construction of bioactive organic moieties

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.