Reformatskytype

The Reformatsky reaction is an organozinc-based reaction in organic chemistry that involves the reaction of an alpha-halo ester with a carbonyl compound in the presence of zinc metal. This reaction yields a beta-hydroxy ester. It is a valuable method for carbon-carbon bond formation and is particularly useful for creating complex molecules. The reaction is named after the Russian chemist Sergei Reformatsky, who first reported it in 1887.

The mechanism involves the oxidative insertion of zinc into the carbon-halogen bond of the alpha-halo ester, forming an organozinc enolate intermediate. This enolate then acts as a nucleophile, attacking the electrophilic carbon of the carbonyl compound. Subsequent protonation of the alkoxide intermediate by an acidic workup leads to the formation of the beta-hydroxy ester. The reaction is typically carried out in ethereal solvents such as diethyl ether or tetrahydrofuran.

Commonly used alpha-halo esters include ethyl bromoacetate and methyl chloroacetate. Aldehydes and ketones are the most frequent carbonyl partners. The reaction is generally regioselective and stereoselective under certain conditions. It can be advantageous over the Grignard reaction or organolithium reactions in cases where the starting materials might be sensitive to stronger bases or nucleophiles. Variations of the Reformatsky reaction exist, including the use of different metals or activated zinc species to improve reactivity and yield. The product, a beta-hydroxy ester, can be further transformed into other functional groups, such as alpha,beta-unsaturated esters through dehydration, or gamma-lactones via cyclization.