Synthesis of Substituted Tetrahydrochromenes by the Reactions of α,β-Unsaturated Cyanoesters with Dimedone/1,3-Cyclohexanedione

Abstract Ethyl esters of 2-cyano-3-arylacrylic acid 1a–d (a = 4-CH3-C6H4-, b = 4-N(CH3)2-C6H4-, c = 2-CH3O-C6H4-, d = 2-Cl-C6H4-) reacted with 5,5-dimethyl-1,3-cyclohexanedione (2p, Y=CH3), and 1e–g (e = 4-CH3-C6H4-, f = 2-CH3O-C6H4-, g = 2-Cl-C6H4-) reacted with 1,3-cyclohexanedione (2q, Y=H) in the presence of alcoholic sodium ethoxide to give the corresponding ethyl esters of 2-amino-7,7-dimethyl-5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromene-3-carboxylic acid 4a–d and 2-amino-5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromene-3-carboxylic acid 4e–g. The structures of the compounds 4a–g were confirmed by their ultraviolet, infrared, 1H NMR, 13C NMR, and mass spectral data and elemental analyses.