Sauron
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Registered: 22-12-2006
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Beckmann Rearrangement Revisited
Lidia de Luca and coworkers reported a mild, quantitative Beckmann rearrangement of ketoximes to amides and aldoximes to nitriles.
Her reagent is my fave TCT/DMF complex, reacted with 1 equivalent of the carbonyl compound in DMF.
The reaction is rapid for acetophenones and cyclohexanones but slower (24 hrs) for other ketones. The aldoxime reactions are rapid.
Acetophenones are converted to acetanilides, which can be hydrolyzed to anilines.
cyclohexanones give caprolactams.
cyclopentanones give piperidine-2-ones. This has been subject of a previous thread (moribund since last year) but no mention was made of this reagent,
only the classically harsh and troublesome Beckmann conditions.
The ability to convert a substituted acetophenone oxime directly to the corresponding substituted acetanilide, affording easy access to the aniline,
ought to be of great utility.
For example the oxime of 2-acetylbenzoic acid can be converted this way, \in one step, to N-acetylanthranilic acid, a desirable compound difficult to
purchase Other routes to anthranilic acid are longer and more difficult.
Article is attached.
[Edited on 18-4-2007 by Sauron]
Attachment: beckmann_rearrgmnt[1].pdf (72kB)
This file has been downloaded 920 times
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