One-pot domino syntheses of 3-alkyl-3- N -substituted aminobenzofuran-2(3 H )-ones based on alkali-promoted Michael addition and lactonization

Abstract

In this paper, a novel cascade reaction of caesium carbonate-promoted Michael addition and lactonization for the one-pot synthesis of 3-alkyl-3- N -substituted aminobenzofuran-2(3 H )-one derivatives has been established based on the screening of the alkaline reagents and optimization of reaction conditions, in which the N -substituted ( ortho -hydroxy)aryl glycine esters were used as the Michael donors to react with different α , β-unsaturated carbonyl compounds. In the case of using the asymmetric starting material, the epimers could be successfully separated by conventional chromatography. In addition, plausible mechanisms were suggested and the absolute configuration of the epimer was analysed. All the chemical structures of unreported benzofuran-2(3 H )-one derivatives were characterized by 1 H nuclear magnetic resonance (NMR), 13 C NMR, IR and high-resolution mass spectrometry (HRMS).