Synthesis of Trans‐4a,12b/3,4‐Dihydrodibenzo[f,h]quinolin‐2(1H)‐Ones and Dibenzo[f,h]quinolin‐2(1H)‐Ones via Irradiation of 6‐Biphenylpyridine‐2(1H)‐Ones

AbstractThe synthesis of trans‐4a,12b‐dihydrodibenzo[f,h]quinolin‐2(1H)‐ones (2), dibenzo[f,h]quinolin‐2(1H)‐ones (3) and 3,4‐dihydrodibenzo[f,h]quinolin‐2(1H)‐ones (4) via photo‐induced annulation of 6‐([1,1′‐biphenyl]‐2‐yl)pyridine‐2(1H)‐ones (1) under irradiation of a 313 nm UV light was described. Compounds 2 were obtained in 82–95% yields when the irradiation time was 3 h. Products 3 were obtained by irradiating 1 for 12 h in the presence of iodine. Heating the solutions of 2 in DMF at 130 °C for 24 h gave compounds 4 via a double 1,3‐H shift. The demonstrated protocols showed the diversity of photo‐induced cyclization of compounds 1.magnified image