MECHANISTIC ASPECTS OF LUMIKETONE PHOTO-REARRANGEMENT OF 4, 4-DISUBSTITUTED CYCLOHEXENONE SYSTEMS-A REVIEW

Abstract

The photochemistry of α,β-unsaturated ketone is rich and varied with many facets of mechanistic interest. Cyclic α,β- enones, especially those with a six membered ring, undergo a number of photochemical reactions due to presence of energetically similar two triplet states 3(π,π*) and 3(n,π*). Among the different photoreactions of α,β-enones, Type A or Lumiketone rearrangement are very common in 4,4-disubstituted cyclohexenones. The mechanism of ketonelumiketone rearrangement was a subject of extensive research for several years and both of the concerted and stepwise (radicaloid) mechanism has been discussed in detail in this review.