A Convenient and Simple Method for the Synthesis of Condensed γ-Lactams and Substituted Xanthones from Cyclic-1,3-diketones

A systematic study of alkylation of cyclic-1,3-diones with 2-bromo-6-methoxybenzofuran-3-one was undertaken. Upon condensation in acetic acid with p-substituted aniline the O-alkylated product 3a gave condensed γ-lactam heterocycle 4. In contrast, the condensation of analogous O-alkylated derivatives 3b and 3c with p-substituted anilines furnished the substituted xanthone derivatives 6 and 7a. The probable mechanism of formation of 4, 6 and 7a was discussed.