998-83-4Relevant academic research and scientific papers
An investigation of the reactions of substituted homoallylic alcohols with various oxidation reagents
Servi,Acar
, p. 104 - 111 (2007/10/03)
Substituted homoallylic alcohols have been synthesised both by [2,3]-Wittig rearrangement of unsymmetrical bis-allylic ethers and reaction of alkenyl chloromethyl oxiranes with Mg/THF. These substrates were then oxidized using four different oxidants. When the substituted homoallylic alcohols were oxidized with pyridinium chlorochromate or zinc chlorochromate nonahydrate the corresponding carbonyl compounds were produced. The same substrates formed the corresponding allylic oxidation products together with epoxidation products when oxidized with t-BuOOH. When and t-BuOOH and catalytic amounts of OsO 4 were used the allylic oxidation reaction was prevented and the only products formed were those in which the substituted double bond was epoxidized.
Oxidation of substituted 1,5-hexadien-3-ols with various oxidants
Servi,Cansiz,Acar,Koparir
, p. 1542 - 1548 (2007/10/03)
Substituted 1,5-hexadien-3-ols were synthesized by the [2,3]-Wittig rearrangement of unsymmetrical bis-allyl ethers, as well as by reactions of 1-(2-alkenyl)-2-chloromethyloxiranes with Mg/THF. The products were oxidized with pyridinium chlorochromate (PCC), zinc chlorochromate (ZCC), tert-butyl hydroperoxide in the presence of OsO4, and tert-butyl hydroperoxide alone. The oxidation of substituted 1,5-hexadien-3-ols with PCC and ZCC gave the corresponding carbonyl compounds. In the reaction with tert-butyl hydroperoxide catalyzed by OsO4 the internal double bond in the substrate was regioselectively converted into epoxy group, whereas allylic oxidation was prevented.
Photochemistry of 1,5-hexadien-3-ones: Wavelength-dependent selectivity in intramolecular enone-olefin photoadditions
Dauben, William G.,Cogen, Jeffrey M.,Ganzer, George A.,Behar, Victor
, p. 5817 - 5824 (2007/10/02)
The photochemistry of ten 1,5-hexadien-3-ones in methanol is studied over the wavelength range of 313-366 nm, by using monochromatic light. With the goal of understanding the unusual wavelength-dependent selectivity observed for 5-methyl-1,5-hexadien-3-one (1), quantum yield measurements, structure reactivity studies, triplet sensitization, and quenching experiments are performed. While six of the ten dienones studied show selectivities that are independent of irradiation wavelength from 313 to 366 nm, four of the dienones exhibit wavelength-dependent selectivities that are similar to that observed in 1, thus establishing that 1 is not unique, as previously believed. Triplet sensitization studies suggest that the wavelength dependence results, largely, from a single-state α-cleavage reaction that competes with triplet cycloaddition. A variety of triplet quenchers were ineffective at inhibiting these reactions. Some possible mechanisms are discussed.
