its all about organometallic chemistry of zinc and copper metal
Reaction of Organozinc compounds The Reformatsky Reaction • Important: conversion of β-hydroxy esters to α,β-unsat. esters • Acid-cat. dehydration gives α,β- + β,γ-unsaturated esters mixture • However, conversion of the initially formed β-hydroxy esters to their corresponding acetates by treatment with acetyl chloride, followed by base-catalyzed dehydration with NaOEt, produces conjugated esters in high purity.
Reaction of Organozinc compounds The Reformatsky Reaction • β-Hydroxy esters and α,β−unsaturated esters may also be prepared either via a single-step Barbier-type condensation of a t-Bu-bromoester with carbonyl compounds in the presence of Mg metal or via a two-step condensation with Lienolates