Revisiting the Synthesis of Betti Bases: Facile, One-pot, and Efficient Synthesis of Betti Bases Promoted by FeCl3•6H2O

Abstract

Background: Betti bases are pharmaceutically and synthetically important scaffolds due to their diverse range of biological activities and applications in key synthetic transformations in organic synthesis. Objective: This work has been sought to contribute to the development, design, and implementation of an improved green methodology with higher atom economy and lower E-factor values for the synthesis of Betti bases. Method: To realize our objectives, we screened out different catalysts and reaction conditions using one-pot multicomponent modified Mannich reaction/Betti reaction by employing 2-naphthol, benzaldehyde and pyrrolidine as model substrates. Results: The developed methodology afforded functionalized Betti bases in 60-100% yields via FeCl3•6H2O catalyzed one-pot multi-component Betti reaction under neat conditions at 110 °C (5-15 min) using several aromatic aldehydes and secondary amines. Conclusion: A facile synthetic methodology with higher atom economy and lower E-factor values to synthesize Betti bases via FeCl3•6H2O catalyzed one-pot multicomponent Betti reaction of 2-naphthol, aromatic aldehydes, and secondary amines under neat conditions at 110 °C has been reported. The developed methodology offers various advantages, such as excellent yields (60-100%), short reaction time (5-15 min), wide substrate scope (12 examples), green reaction conditions, use of readily available catalyst, and easy purification (without column chromatography).