Intramolecular amidation — An efficient synthesis of 3-aryl-2-quinolinones

Abstract

To reveal the scope of the syntheses of 3-aryl-2-quinolinones from 2-nitro-α-phenylcinnamic acids, the isomerization of (E)-2-amino-α-phenylcinnamic acids was studied. The results showed that (E)-2-amino-α-phenylcinnamic acids were isomerized to its (Z)-forms under sunlight in organic solvents. The reaction temperature and the functional groups at both phenyl rings have no effect on the isomerization of (E)-2-amino-α-phenylcinnamic acids and the following intramolecular spontaneous amidation of (Z)-2-amino-α-phenylcinnamic acids. Various 3-aryl-2-quinolinones prepared in high total yields indicated that the syntheses of 3-aryl-2-quinolinones from Perkin condensation products 2-nitro-α-phenylcinnamic acids via reduction, sunlight-induced isomerization of (E)-2-amino-α-phenylcinnamic acids, and the following intramolecular amidation is an efficient procedure. Key words: 3-aryl-2-quinolinones, isomerization, amidation.