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Haloketone



A haloketone in organic chemistry is a functional group consisting of a ketone group or more general a carbonyl group with a α-halogen substituent. The general structure is RR'C(X)C(=O)R where R is an alkyl or aryl residue and X any one of the halogens. The preferred conformation of a haloketone is that of a cisoid with the halogen and carbonyl sharing the same plane as the steric hindrance with the carbonyl alkyl group is generally larger [1].

Additional recommended knowledge

Contents

Haloketone synthesis

Asymmetric synthesis

Efforts are reported in asymmetric synthesis of halocarbonyls through organocatalysis. In one study an acid chloride is converted into an α-halo-ester with a strong base (sodium hydride), a bromine donor and an organocatalyst based on proline and quinine [2]:

In the proposed reaction mechanism the base first converts the acid chloride to the ketene, the organocatalyst then introduces chirality through its quininoid tertiary amine, forming a ketene adduct.

Haloketone reactions

Haloketones take part in several reaction types. In reaction with a nucleophile 2 electrophilic sites are available and in reactions with a base several acidic protons exist due to the presence of two electron withdrawing groups. The carbon halogen bond experiences increases polarity from the inductive effect of the carbonyl group making the carbon atom more electropositive.

See also

References

  1. ^ The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis Ayman W. Erian, Sherif M. Sherif and Hatem M. Gaber Molecules 2003, 8, 793-865 Online Article
  2. ^ Scalable Methodology for the Catalytic, Asymmetric -Bromination of Acid Chlorides Cajetan Dogo-Isonagie, Tefsit Bekele, Stefan France, Jamison Wolfer, Anthony Weatherwax, Andrew E. Taggi, and Thomas Lectka J. Org. Chem.; 2006; 71(23) pp 8946 - 8949; (Note) doi:10.1021/jo061522l
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Haloketone". A list of authors is available in Wikipedia.
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