51468-87-2Relevant articles and documents
Photochemical Reactions. 137-th Communication. Preparation and Photolysis of (E/Z)-7-Methyl-β-ionone
Ishii, Keitaro,Mathies, Peter,Nishio, Takehiko,Wolf, Hans Richard,Frei, Bruno,Jeger, Oskar
, p. 1175 - 1183 (2007/10/02)
The title compounds (E/Z)-7 were prepared in 66percent overall yield by reaction of β-ionone ((E)-1) with lithium dimethylcuprate, trapping of the intermediate enolate with benzeneselenyl bromide and oxidation with H2O2.Analogously, (E/Z)-7-methyl-α-ionone ((E/Z)-12) was obtained in 65percent yield from α-ionone ((E)-11). 1n,?*-Excitation (λ > 347 nm, pentane) of (E)-7 causes rapid (E/Z)-isomerization and subsequent reaction of (Z)-7 to 15 (66percent).The formation of 15 is explained by twisting of the dienone chromofore due to repulsive interaction of the 7-CH3-group with the CH3-groups of the cyclohexene ring.On the other hand, irradiation, (λ > 347 nm, Et2O) of (E)-7 in the presence of acid leads to (Z)-7 (5percent) and to the novel compound 16 (88percent).
