Transformations in the 2-quinolone series

The treatment of 1-substituted-1,2-dihydro-4-hydroxy-2-oxo-3-quinoline carboxylic acid esters and 4-hydroxy-1-methyl-3-nitro-2-(1H)quinolinone with phosphorus oxychloride resulted in the formation of the corresponding 4-chloro-2-quinolones. Their reactions with a variety of carbon, nitrogen, oxygen, and sulfur nucleophiles is described.