Photochemistry of 2,5-cyclohexadienones

Still another example of bond order control of photochemical reactivity is found in the photochemistry of 2,5-cyclohexadienones. Here, strong evidence suggests that the n-7t excited triplet is the species responsible for the rearrangement6,12,17 23). It is seen that the critical step is P, (3-bonding in the excited state. The reaction mechanism is depicted in Scheme 2. 

Schultz carried out extensive studies exploiting the rich photochemistry of 2,5-cyclohexadienones to generate complex multi-cyclic systems amenable to further synthetic elaboration. These studies have explored the intramolecular photocycloadditions of 2,5-cyclohexadienone with alkene and diene traps appended to the 4-position of the ring. This work has been previously reviewed. This chapter focuses on the ability to capture the transient oxyallyl species. 

Photochemistry of 1-dehydrotestosterone acetate and its methyl derivatives begins with conversion of 2, 5-cyclohexadienones (XVI) into a bicyclo [3.1.0] hexenone (XVII) and then to new cyclohexadienone (XVIII) of assigned... 

The mechanistic photochemistry of cross-conjugated 2,5-cyclohexadienones has been comprehensively examined (Scheme 21). The photochemical isomerization of the... 

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