Photochemical reactions of 1‐methyl‐4,6‐diaryl‐2(1 H )‐pyrimidinones in the presence of thiols

Photochemical reactions of 1‐methyl‐4,6‐diaryl‐2(1 H )pyrimidinones 1a‐b in the presence of thiols 2 are described. Irradiation of 1‐methyl‐4,6‐diaryl‐2(1 H )‐pyrimidinones 1a‐b in benzene in the presence of thiols 2 gave the unexpected 2:1‐adducts, 3‐methyl‐4,6‐diaryl‐5‐aralkylthio‐6‐(1′‐methyl‐4′,6′‐diaryldihydro‐pyrimidin‐2‐on)yl‐1,3‐diazabicyclo[2.2.0]hexan‐2‐ones 3‐6, of 1 and 2, whereas irradiation of 1a‐b alone in benzene resulted in recovery of the unchanged 1a‐b.