Facile and Green Synthesis of 1,4-Dihydropyridine Derivatives in n-Butyl Pyridinium Tetrafluoroborate

Abstract

l,4-Dihydropyridine derivatives were synthesized from the one-pot condensation of aldehydes, acetoacetates, and ammonium acetate in room-temperature ionic liquid n-butyl pyridinium tetrafluoroborate ([BPy][BF₄]). Compared with classical Hantzsch reaction conditions, this new method has the advantage of excellent yields, short reaction time, and easy workup. The recovered ionic liquid could be recycled for at least five runs without losing its activity.

GRAPHICAL ABSTRACT

Keywords:

• 1,4-Dihydropyridine
• ionic liquid
• one-pot condensation

ACKNOWLEDGMENT

This work was financially supported by the Medical Scientific Research Fundation of Guangdong Province (No. B2007112).

Notes

^a Reactions were conducted with 3-nitrobenzaldehyde (20 mmol), methyl acetoacetate (40 mmol), and ammonium acetate (30 mmol) in [BPy][BF₄] (10 mL).

^a Reactions were conducted under reflux in ethanol.

^b Isolated yields.