Cyclobutanes Wurtz reaction

Cyclobutanes may also be prepared by this type of Wurtz reaction, but the approach is not successful for carbocyclic ring sizes greater than four. Studies of the reagents able to generate cyclobutane from 1,4-dihalo substrates have indicated that the use of Li/Hg amalgam in dioxane at high temperature gives the best yield. °... 

The intramolecular Wurtz-type coupling of dihaloorganic compounds with use of metallic zinc is a classical synthetic route to cyclic compounds. For example, cyclopropane derivatives can be prepared from 1,3-dihalo-propanes (29, 189a, 248, 451), and cyclobutane derivatives from 1,4-dihalobutanes (71). These reactions presumably proceed via the intermediate formation of organozinc compounds. The reaction of diethylzinc with esters of a,a -dibrominated aliphatic dicarboxylic acids leads to the... 

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