Glycerin mediated-synthesis of 2-amino-4-aryl-3-cyano-4H-pyran derivatives

Background: Polyfunctionalized 4H-pyrans are an important class of organic compounds due to their useful biological and pharmacological activities [1] such as antiallergic, antitumor, antibacterial activity, as potentially biodegradable agrochemicals, a structural unit of many natural products, and potential calcium channel antagonists [2].Methods: In a one neck flask, ethyl acetoacetate (1 mmol), aryl aldehydes (1 mmol)and malononitrile (1 mmol) were mixed in glycerin and ethyl amine (1 ml) at 100 ºC.After completion of the reaction monitored by TLC, water was added and the product was obtained as a solid compound. The desired product was resulted after filtration, dried and recrystallized by ethanol and identified by Perkin Elmer FT-IR spectrometer and P1PHNMR spectra on Bruker DRX- 300 MHZ NMR instrument.Results: Aromatic aldehydes, malononitrile and ethyl acetoacetate were used in the synthesis of 2-amino-4-aryl-3-cyano-4H-pyran derivatives in glycerin and ethyl amine at100 ºC under reflux condition (Scheme 1). The experimental procedure is very simple and represents an attractive alternative to existing methods. This reaction protocol has the potential for developing combinatorial libraries.