Chemical Sciences: A Manual for CSIR-UGC National Eligibility Test for Lectureship and JRF/Named Reactions/Reformatsky Reaction

The Reformatsky reaction (sometimes spelled Reformatskii reaction) is an organic reaction which condenses aldehydes (or ketones), 1, with α-halo esters, 2, using a metallic zinc catalyst to form β-hydroxy-esters, 3. It was discovered by Sergey Nikolaevich Reformatsky.



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

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 derviative adopts a tub-shaped conformation and has cis bromo groups and cis THF ligands, whereas in the tert-butyl derviative, the ring is in a chair form and the bromo groups and THF ligands are trans.

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