Synthesis of Oxadihydrophenanthroquinolizidinones by Photoinduced Rearrangement of 3‐Biphenyl‐1‐hydroxypropyl‐pyridin‐2(1H)‐ones

The synthesis of hexahydro‐11H,15H‐dibenzo[f,h] [1,3]oxazino[3,2‐b]isoquinolin‐15‐ones was achieved via photoinduced rearrangement of 3‐biphenyl‐1‐hydroxypropyl‐pyridin‐2(1H)‐ones with a 313 nm UV light. Trans‐(8b,15a)‐9a‐β‐hexahydro‐11H,15H‐dibenzo[f,h][1,3]oxazino[3,2‐b]isoquinolin‐15‐ones and trans‐(8b,15a)‐9a‐α‐hexahydro‐11H,15H‐dibenzo[f,h][1,3] oxazino[3,2‐b]isoquinolin‐15‐ones were obtained in 76‐92% yields via a one‐pot reaction. Alternatively, irradiation of 3‐biphenyl‐1‐hydroxypropyl‐pyridin‐2(1H)‐ones in the presence of HCl aqueous solution (1 M) led to the formation of cis‐(8b,15a)‐9a‐β‐hexahydro‐11H,15H‐dibenzo[f,h][1,3]oxazino[3 ,2‐b]isoquinolin‐15‐ones and cis‐(8b,15a)‐ 9a‐α‐hexahydro‐11H,15H‐dibenzo[f,h][1,3]oxazino[3,2‐b]isoquinolin‐15‐ones by a one‐pot reaction of photo 6π‐electrocyclization and addition cyclization. The construction of a partially dearomatized phenanthrene ring and quinolizidinone ring was achieved by a one‐pot reaction, with controlled cis/trans stereochemistry.