Ring-opening reaction of methylenecyclopropanes with LiCl, LiBr or NaI in acetic acid

The methylenecyclopropanes react with LiCl, LiBr or NaI at 80 °C to give the corresponding gem-disubstituted homoallylic halides in good to excellent yields in acetic acid. In some cases, the ring-opening reaction can be completed within 5 min to give the corresponding gem-disubstituted homoallylic halides in high yields.