Photochemistry of 4,4-exo-6-trimethyl-1-phenyl-3-oxabicyclo[3,1,0]hexan-2-one. Formation of a keten intermediate
The photochemistry (λ 254 nm) of exo-(1) was examined. In nonhydroxylic solvents an αβ-unsaturated lactone (2) was formed. In hydroxylic solvents a βγ-unsaturated ester (3) was also formed, which is proposed to arise from a keten intermediate. Upon acetone-sensitized irradiation of exo-(1) only exo–endo isomerization occurs.