Reformatsky reaction

The Reformatsky reaction (sometimes spelled Reformatskii reaction) is an organic reaction which condenses aldehydes or ketones, with α-halo esters, using a metallic zinc to form β-hydroxy-esters:

The Reformatsky reaction

The organozinc reagent, also called a 'Reformatsky enolate', is prepared by treating an alpha-halo ester with zinc dust. Reformatsky enolates are less reactive than lithium enolates or Grignard reagents and hence nucleophilic addition to the ester group does not occur. The reaction was discovered by Sergey Nikolaevich Reformatsky.

Some reviews have been published.

Structure of the reagent

The crystal structures of the THF complexes of the Reformatsky reagents tert-butyl bromozincacetate and ethyl bromozincacetate have been determined. Both form cyclic eight-membered dimers in the solid state, but differ in stereochemistry: the eight-membered ring in the ethyl derivative adopts a tub-shaped conformation and has cis bromo groups and cis THF ligands, whereas in the tert-butyl derivative, the ring is in a chair form and the bromo groups and THF ligands are trans.

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ethyl bromozincacetate dimer	tert-butyl bromozincacetate dimer

Variations

In one variation of the Reformatsky reaction an iodolactam is coupled with an aldehyde with triethylborane in toluene at -78°C.

Reformatsky reaction Danishefsky variation[7]

See also

• Example use in total synthesis: Mukaiyama Taxol total synthesis (B ring construction)

See also

• Aldol reaction
• Blaise reaction
• Claisen condensation