Synthesis of substituted N‐(2,4‐dioxo‐1,2,3,4‐tetrahydroquinazolinyl)benzamides and N‐(2‐thiono‐4‐oxo‐1,2,3,4‐tetrahydroquinazolinyl)benzamides

Substituted N‐(2,4‐Dioxo‐1,2,3,4‐tetrahydroquinazolinyl)benzamides (3a‐g) and substituted N‐(2‐Thiono‐4‐oxo‐1,2,3,4‐tetrahydroquinazolinyl)benzamides (4a‐g) were synthesized in one step from the reaction of methyl anthranilate with 2‐aryl‐1,3,4‐oxadiazolin‐5‐ones (1a‐g) and 2‐aryl‐1,3,4‐oxadiazoline‐5‐thiones (2a‐g), respectively, in m‐cresol at 150–160°. Alternative routes leading to the formation of 3a and 4a are also reported.