A Mild and Efficient Synthesis of 4-Quinolones and Quinolone Heterocycles

The cycloacylation of aniline derivatives to 4-quinolones in the presence of Eaton's reagent is described. This high-yielding methodology is applicable to a wide variety of functionalized anilines and requires milder conditions than those traditionally employed. This cyclization protocol is used to prepare a host of heterocycles and bis-quinolones and is characterized by relatively low reaction temperature and ease of product isolation.