Comparative Study of Catalytic Potential of TBAB, BTEAC, and CTAB in One-Pot Synthesis of 1,4-Dihydropyridines Under Aqueous Medium

Abstract

Convenient and straightforward tetrabutylammonium bromide (TBAB), benzyltrienthylammonium chloride (BTEAC), and cetyltrimethylammonium bromide (CTAB) catalyzed synthesis of 1,4-dihydropyridines (1,4-DHPs) in water was established for the first time. The catalytic potential of phase-transfer catalysts (PTCs) in three different concentrations was envisioned. Aryl aldehydes and hetero aryl aldehydes afforded good yields of 1,4-DHPs in TBAB and BTEAC reactions. In particular, furfuraldehyde and thienyl-2-carbaldehyde produced excellent yields. Isolation of the products through nonchromatographic methods, good to excellent yields, and benign reaction conditions are the major advantages of this protocol.

GRAPHICAL ABSTRACT

Keywords:

• 1,4-Dihydropyridines
• Hantzsch reaction
• phase-transfer catalyst
• water reaction

ACKNOWLEDGMENTS

The authors gratefully acknowledge the president, Gokaraju Rangaraju Educational Society, Hyderabad, and the chairman, IICT, Hyderabad, for their support.

Notes

Notes. TBAB, tetrabutylammonium bromide; BTEAC, benzyltriethylammonium chloride; CTAB, cetyltrimethylammonium bromide. Molar ratios of reactants: benzaldehyde, 1 mmol; ethyl acetoacetate, 2 mmol; ammonium acetate, 2 mmol; PTC, 10 mol%.

Notes. TBAB, tetrabutylammonium bromide; BTEAC, benzyltriethylammonium chloride; CTAB, cetyltritmethylammonium bromide.

Notes. TBAB, tetrabutylammonium bromide; BTEAC, benzyltriethylammonium chloride; CTAB, cetyltrimethylammonium bromide.

Notes. TBAB, tetrabutylammonium bromide; BTEAC, benzyltriethylammonium chloride; CTAB, cetyltrimethylammonium bromide.

Notes. Quantity of reactants for 1-fold: benzaldehyde, 10 mmol, ethyl acetoacetate, 20 mmol; ammonium acetate, 20 mmol; water, 2 ml; TBAB, 10 mol%.