An Efficient Propylphosphonic Anhydride (T3P®)-Mediated MW-induced Solvent-free Rapid Synthesis of Enamino Esters and Ketones including 5,5- Dimethyl-3-aminocyclohex-2-enones

Abstract

Abstract: This work presents a clean and convenient synthesis of various β-enaminones including 5,5- dimethyl-3-aminocyclohex-2-enones, in satisfactory to excellent yields from the condensation reaction of primary amines with β -dicarbonyls by employing T3P® as a catalyst and performing the reaction under microwave irradiation and solvent-free conditions. These rapid reactions launched readily and stood a diversity of organic functional groups. A mixture of 1,3-dicarbonyl compound, primary amine and T3P® (50% in AcOEt) was irradiated for an appropriate time under microwave at 80°C. After completing the reaction (TLC) and cooling to r.t., ethyl acetate and saturated aqueous NaHCO3 solution were added. The aqueous phase was extracted ethyl acetate. The combined organic layer was washed with brine, dried over Na2SO4, and filtered, and the solvent was removed under reduced pressure to afford the product, which was recrystallized from diisopropyl ether. The presented results exhibit a better catalytic activity of T3P in the synthesis of enaminones. It could be concluded that T3P is the best catalyst as it took only a few minutes for the completion of the reaction with an excellent yield of product, which indicates T3P is more efficient, compared to other catalysts. A comparison of the efficiency of the present procedure with some heterogeneous solid catalysts was evaluated as well. Clearly, a higher yield was established in this procedure compared to other catalysts. Furthermore, the reaction of amines with dimedone was investigated as well, delivering excellent yields. The reaction catalyzed by T3P under microwave irradiation supplies a comprehensive method for the synthesis of enaminones. In this work, T3P is an effective, efficient and green catalyst, which forms the procedure economic, suitable, and safe with widespread application in the synthesis of enaminones. background: This work presents a clean and convenient synthesis of various β-enaminones incuding 5,5-dimethyl-3-aminocyclohex-2-enones in good to excellent yields from the reaction of different primary amines with 1,3-dicarbonyl compounds by employing T3P® as a catalyst and performing the reaction under microwave irradiation and solvent-free conditions. This one-pot rapid reaction proceeded readily and tolerated a variety of functional groups.