| Popis: |
Unsaturated (α,β- and β,γ-) aldehydes and ketones, capable of forming a conjugated dienol can be oxidized under mild reaction conditions in the presence of catalytic amounts of cupric-amine complexes in alkaline methanolic solution. Specific oxidation in the γ-position is thought to occur with formation of a γ-hydroperoxy α,β-unsaturated carbonyl compound as a primary intermediate. The decomposition products of the γ-hydroperoxide depend upon the number of hydrogen atoms attached to the γ-carbon atom. A hydroperoxide group attached to a primary carbon atom is converted into an aldehyde function; likewise a secondary and a tertiary γ-carbon atom lead to a keto and an alcohol function, respectively. The alcohols can be isolated as such, whereas products containing an aldehyde and a keto function form either cyclization products like unsaturated lactones, polyacetals or cyclic ethers or are cleft into esters and aldehydes. The mechanism of the oxidation reaction is discussed briefly. |
