Trimethylsilyl Polyphosphate Promoted Efficient Synthesis of 4(3<i>H)‐</i>Quinazolinones from Methyl Anthranilate

Abstract A trimethylsilyl polyphosphate (PPSE) promoted synthesis of 4(3 H )‐quinazolinones, a heterocycle with wide biological potential, from methyl anthranilate and secondary amides is described. The procedure is general, involves very easily available starting materials, shows functional group tolerance and leads to good to excellent yields. The method proved to be suitable for scaling‐up. A one‐pot approach was also explored. This step‐economic modification reduces the time, waste and environmental impact of the synthesis and leads to satisfactory global yields that include 2 or 3 single steps. Finally, a possible reaction mechanism that involves a nitrilium cation intermediate is proposed.