Oxidation with chromium(VI) complexes: Difference between revisions

Revision as of 15:09, 17 November 2024

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An important process mediated by chromium(VI)-amines is the oxidative transposition of tertiary allylic alcohols to give enones.<ref name=OR/> The mechanism of this process likely depends on the acidity of the chromium reagent. Acidic reagents such as PCC may cause ionization and recombination of the chromate ester (path A), while the basic reagents (Collins) likely undergo direct allylic transposition via sigmatropic rearrangement (path B).

{{center|[[File:ChroMech2.png]]}}

Oxidative cyclizations of olefinic alcohols to cyclic ethers may occur via [3+2], [2+2],<ref>Piccialli, V. ''Synthesis'' '''2007''', 2585.<name=OR/ref> or [[epoxidation]] mechanisms. Insights into the mechanism is provided by structure-reactivity, implicating direct epoxidation by the chromate ester.<ref>Beihoffer, L.A; Craven, R.A.; Knight, K.S; Cisson, C.R.; Waddell, T.G. ''Trans. Met. Chem.'' '''2005''', ''30'', 582.<name=OR/ref> Subsequent epoxide opening and release of chromium leads to the observed products.

==Scope and limitations==