Synthetic Applications of Metal Halides.Conversion of Cyclopropylmethanols into Homoallylic Halides.

Article abstract of DOI:10.1021/jo01301a003

Magnesium and beryllium halides in refluxing diethyl ether effect the transformation of cyclopropylmethanols into homoallylic halides,in contrast to several other metal halides and Lewis acid/nucleophile combinations which were examined.Magnesium bromide and iodide are particularly effective: conditions are mild,yields are high,and little or no byproducts are formed.Tertiary and benzylic alcohols are more reactive than secondary alcohols,while the latter are converted into E homoallylic halides with high stereoselectivity.Cyclopropylmethanol itself fails to react.In the cases of magnesium halide reactions with bicyclo<3.1.0>-2-hexanol and bicyclo<4.1.0>-2-heptanol,addition of an equimolar amount of zinc halide not only caused substantial rate enhancement but also increased regioselectivity.