Cyclopropylmethanols are converted into homoallylic halides in high yield by treatment with magnesium bromide or iodide in refluxing, anhydrous diethyl ether. For uncovering of the details of the reaction mechanism,(cyclopropylpheny1methoxy) magnesium bromide (3a) was prepared by treatment of cyclopropylphenylmethanol (1) with hydridomagnesium bromide. Alkoxymagnesium bromide 3a was stable in refluxing diethyl ether and was not ...