The selective preparation of 1,4‐diaryl‐6‐methyl‐ and 1,6‐diaryl‐4‐methyl‐2‐(1 H )pyrimidinones

N ‐Phenylurea reacted with benzoylacetone derivatives (I) to give 1,4‐diaryl‐6‐methyl‐2‐(1 H )pyrimidinones (II) in addition to low yields of 1,6‐diaryl‐4‐methyl‐2‐(1 H )pyrimidinones (IV), while N ‐phenylthiourea afforded only 1,6‐diaryl‐4‐methyl‐2‐(1 H )pyrimidinethiones (III) in good yields. Further 1,6‐diaryl‐4‐methyl‐2‐(1 H )‐ pyrimidinethiones (III) were successfully converted in satisfactory yields into the corresponding 2‐(1 H )‐pyrimidinones (IV) by the treatment with methyl iodide in the presence of sodium methoxide in methanol at room temperature.