-Naphthoquinone-catalyzed aerobic oxidation of amines to fused pyrimidin-4(3)-ones: a convergent synthetic route to bouchardatine and sildenafil.

A facile access to fused pyrimidin-4(3)-one derivatives has been established by using the metal-free -naphthoquinone-catalyzed aerobic cross-coupling reactions of amines. The utilization of two readily available amines allowed a direct coupling strategy to quinazolinone natural product, bouchardatine, as well as sildenafil (Viagra™) in a highly convergent manner.