79892-19-6

Upstream product

• 89128-17-6 (E)-4-(2',6',6'-trimethyl-1'-cyclohexen-1'yl)-3-penten-2-one 
• 93175-81-6 3-Phenylselanyl-4-(2,6,6-trimethyl-cyclohex-1-enyl)-pentan-2-one 
• 79-77-6 (E)-β-ionone 
• 93175-79-2 (Z)-4-(2',6',6'-trimethyl-2'-cyclohexen-1'yl)-3-penten-2-one 

Downstream Products

• 89128-17-6 (E)-4-(2',6',6'-trimethyl-1'-cyclohexen-1'yl)-3-penten-2-one 
• 89128-14-3 (1R,6R)-1-((Z)-1,3-Dimethyl-buta-1,3-dienyl)-2,2,6-trimethyl-7-oxa-bicyclo[4.1.0]heptane 

Relevant academic research and scientific papers

102. Photochemical Reactions. Wavelenght Dependence of the Photochemistry of 7-Methyl-β-ionone

The wavelenght dependence of the photolysis of 7-methyl-β-ionone ((E)-1) was investigated.Irradiation of (E)-1 with light of λ>347 nm leads primarily to (E/Z)-isomerization followed by transformation to the tricyclic enol ether 3 as the only secondary photoproduct.On photolysis of (E)-1 with light of shorter wavelenght (λ>280 nm or λ=254 nm), however, a series of other products was formed via a) photocyclization of the dienone chromophore (->5), b) photo-enolization (->8), and c) a 1,5-sigmatropic H-shift (->(E/Z)-7).For the structure elucidation of the new produts, 7-methyl-β-ionone ((E)--1) was prepared and irradiated furnishing the corresponding 13C-labelled photoproducts.

Photochemical Reactions. 137-th Communication. Preparation and Photolysis of (E/Z)-7-Methyl-β-ionone

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).