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|Title:||The Alpha-Alkoxyallylation of Activated Carbonyl Compounds: A Novel Variant of the Michael Reaction|
|Author(s):||Hobbs, Steven John|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Five methods of alkoxyallylation at the alpha carbon of activated carbonyl compounds are proposed and explored. The product of alkoxyallylation, which are enol ethers, are protected equivalents of the adducts obtained from the Michael reaction of (alpha),(beta)-enals with activated carbonyl compounds.
Enolic or readily enolizable carbonyl compounds undergo alkoxyallylation upon reaction with ethoxyallene or acetals of (alpha),(beta)-enals at temperatures between 25(DEGREES)C to 200(DEGREES)C. Less acidic activated carbonyl compounds were best alkoxyallylated with the acetals above with nickel(II) acetylacetonate catalyst. The alkoxyallylation of activated carbonyl compounds using (gamma)-alkoxyallyl alcohols and (alpha)- or (gamma)-alkoxy allylic chlorides as electrophiles were briefly explored.
The mechanism of the methods of alkoxyallylation probably involves direct C-allylation of the carbonyl compound on the (alpha)-position of an alkoxyallyl cation or equivalent electrophilic species, or an indirect pathway via O-allylation at the (alpha)-position of the cation, followed by Claisen rearrangement of the resulting (alpha)-alkoxyallyl enol ether. Attempts to prepare these enol ethers by selenoxide elimination at 25(DEGREES)C provided instead the corresponding Claisen rearrangement products. The relationship between these methods of alkoxyallylation, the Michael reaction and appropriated cases of the Claisen rearrangement are also discussed.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2014-12-15|