65164-65-0Relevant academic research and scientific papers
Photochemistry of Acylic βγ-Unsaturated Ketones. Part 4. The Effect of α-Methyl Substitution with Some Hex-4-en-2-ones and 1-Phenylpent-3-en-1-ones
Weerdt, Anton J. A. van der,Cerfontain, Hans
, p. 592 - 597 (2007/10/02)
The photochemistry of the two hex-4-en-2-ones (1a and b), and the three 1-phenylpent-3-en-1-ones (1c-e) have been studied.Upon direct irradiation (1a) shows exclusively (E)-(Z) isomerization, whereas (1b) yields only α-cleavage products, illustrating competition between (E)-(Z) isomerization and α-cleavage for the hex-4-en-2-ones.Upon direct irradiation of (1c) no photochemical reaction is observed, but with (1d and e) products resulting from the α-cleavage reaction are obtained.Upon triplet sensitized irradiation (1a and b) yield the corresponding (Z)-isomers, but (1d) gives α-cleavage products.The difference in α-cleavage abili ty between (1a and c) on the one hand and (1b, d, and e) on the other upon direct irradiation is ascribed to the effect of α-methyl substitution.The difference in the photochemical behaviour of the hex-4-en-2-ones (1a and b) compared with that of the 1-phenylpent-3-en-1-ones (1c-e) is rationalized in terms of differences in the triplet state energy levels of the two types of βγ-enones.
