Abstract
[BPy]H2PO4 was easily prepared and used as an efficient and recyclable catalyst for the one-pot synthesis of 2,4,5-trisubstituted imidazoles under solvent-free conditions in good to excellent yields. Solvent-free conditions, simple experimental and workup procedures, and the use of a nontoxic, recyclable catalyst of an environmentally benign nature are remarkable features of the procedure.
ACKNOWLEDGMENT
We thank the Natural Science Foundation of Hubei Province (grants 2007ABA291, 2008CDB036) for financial support.
Notes
a Reaction condition: benzaldehyde (5 mmol), benzil (5 mmol), ammonium acetate (10 mmol) in presence of [BPy]H2PO4 under solvent-free conditions.
b Isolated yield.
a Reaction condition: benzaldehyde (10 mmol), benzil (10 mmol), ammonium acetate (20 mmol), [BPy]H2PO4 (15 mol%) at 130°C under solvent-free conditions.
b Isolated yield.
a Reaction condition: Aromatic aldehyde (5 mmol), benzil (5 mmol), ammonium acetate (10 mmol), [BPy]H2PO4 (15 mol%) at 130°C under solvent-free conditions.
b Isolated yield.