A facile and expedient microwave-assisted solvent-free method for the synthesis of 2-amino-4-(2-oxo-2H-chromen-3-yl)nicotinonitriles
An efficient method for the synthesis of novel 2-amino-4-(2-oxo-2H-chromen-3-yl)nicotinonitriles has been developed under solvent-free conditions using enaminonitriles and various aliphatic amines. 3-acetyl-2H-chromen-2-one (1) reacted with malononitirle in ethanol using l-proline as a base to give 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)malononitrile (2) which on reaction with dimethylformamide dimethyl acetal (DMF-DMA) resulted in the formation of 2-(3-(dimethylamino)-1-(2-oxo-2H-chromen-3-yl)allylidene)malononitrile (3). The later on reaction with various aliphatic amines under solvent-free conditions gave the title compounds, i.e., 2-amino-4-(2-oxo-2H-chromen-3-yl)nicotinonitriles (4). Microwave irradiation method has also been applied successfully to achieve the compounds in excellent yields.
KeywordsCoumarins 2-Amino-3-cyanopyridines Solvent-free method Microwave irradiation
The authors are thankful to the authorities of Jawaharlal Nehru Technological University Hyderabad for providing laboratory facilities. They are grateful to the Department of Science & Technology, Govt. of India, New Delhi, for the financial support in the form of INSPIRE Fellowship to one of them (D.S.).