[reaction: see text] Several new routes for the preparation of 3-amino-2-phenyl-4-1(H)-quinolinone 7a are compared. The most efficient is based on the cyclization of phenacyl anthranilamide 2a in the presence of (poly)phosphoric acid. The mechanisms of the rearrangements involved are discussed on the basis of the structures of isolated heterocyclic intermediates. The best methodology for the preparation of the title compound 7a was verified, and 10 other quinolinones 7 were prepared.

Department of Organic Chemistry Palacký University Tr Svobody 8 771 46 Olomouc Czech Republic

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Novel Schiff bases based on the quinolinone skeleton: syntheses, X-ray structures and fluorescent properties