Intramolecular photorearrangement of a 2-alkenyl-4-chromanone to an oxapentacyclotetradecanedione

A novel transformation of 7-hydroxy-2-methyl-2-(4-methyl-3-pentenyl)-4-chromanone ( 1 ) to intramolecular 1,3-arene-alkene photocycloadduct, (1 S ,2 R ,5 S ,7 S ,10 S ,13 R )6,6,10-trimethyl-14-oxapentacyclo[8.3.1.0 1,7 .0 2,13 0 5,13 ] tetradecane-3,12-dione ( 3 ) via secondary photorearrangement of 1,2-arene-alkene photocycloadduct ( 2 ) has been described.