Zur Photochemie von ( Z , Z )‐2,7‐Cyclodecadien‐1‐on und 4,8‐Cyclododecadien‐1‐on. Synthese und Eigenschaften von Tricyclo[5.3.0.0 2,8 ]decan‐Systemen

On the Photochemistry of ( Z , Z )‐2,7‐Cyclodecadien‐1‐one and 4,8‐Cyclododecadien‐1‐one. Synthesis and Properties of Tricyclo[5.3.0.0 2,8 ]decane Systems Irradiation of ( Z , Z )‐2,7‐cyclodecadien‐1‐one ( 3 ) yields ( Z , Z )‐3,7‐cyclodecadien‐1‐one ( 12 ) or tricyclo‐[5.3.0.0 2,8 ]decan‐4‐one ( 16 ), depending on the reaction conditions. Irradiation of 4,8‐cyclododecadien‐1‐one ( 28 ) results also in a light‐induced transannular [2 + 2] cycloaddition, yielding tetracyclo[7.3.0.0 2,10 0 3,6 ]dodecan‐1‐one ( 30 ). Starting from 16 , the preparation of tricyclo[5.3.0.0 2,8 ]dec‐4‐ene ( 19 ), tricyclo[5.3.0.0 2,8 ]dec‐4‐ene ( 21 ) and tricyclo[5.3.0.0 2,8 ]deca‐3,5‐diene ( 24 ) is described. The 1 H‐NMR and 13 CNMR spectra of the newly prepared compounds are discussed. In the case of 19, 21 , and 24 , the electronic structure is discussed on hand of their PE spectra.