Oxidation with chromium(VI) complexes: Difference between revisions

Revision as of 03:08, 15 June 2010

Revision as of 03:09, 15 June 2010

Line 24:

<span style="float:right;padding-right:50px;padding-top:30px;">'''''(6)'''''</span><center>[[File:ChroScope2.png]]</center>

Enones can be synthesized from tertiary allylic alcohols through the action of a variety of chromium(VI)-amine reagents. The reaction is driven by the formation of a more substituted double bond. (E) enones form in greater amounts than (Z) isomers due to chromium-mediated geometric isomerization.

<span style="float:right;padding-right:50px;padding-top:30px10px;">'''''(7)'''''</span><center>[[File:ChroScope3.png]]</center>

Suitably substituted olefinic alcohols undergo oxidative cyclization to give tetrahydrofurans. Further oxidation of these compounds to give tetrahydropyranyl carbonyl compounds may occur.

<span style="float:right;padding-right:50px;padding-top:30px;">'''''(8)'''''</span><center>[[File:ChroScope4.png]]</center>

Line 42:

===Example Procedure<ref>Guziec, F. S., Jr.; Luzzio, F. A. ''J. Org. Chem.'', '''1982''', ''47'', 1787.</ref>===

To a suspension of 4-(dimethylamino)pyridinium chlorochromate (1.24 g, 4.8 mmol) in dry dichloromethane (7.0 mL) was added p-(3-hydroxypropyl)-benzyl alcohol (200 mg, 1.2 mmol). Stirring was continued (2 hours) at room temperature under a [[nitrogen]] atmosphere. The reaction mixture was diluted with [[ethyl acetate]] (10 mL) and the brown granular [[chromium]] reduction products were removed by vacuum filtration through a [[Celite]]® pad. Concentration of the solvent and [[column chromatography]] on [[silica gel]] ([[hexane]]/[[ethyl acetate]], 2:1) furnished 121 mg (62%) of p-(3-hydroxypropyl)benzaldehyde as an oil.

<span style="float:right;padding-right:50px;padding-top:30px10px;">'''''(9)'''''</span><center>[[File:ChroEx.png]]</center>

==References==