Preparation of functionalized alkenylmagnesium bromides via a bromine–magnesium exchange

α-Bromonitriles, such as 1, 2 or the α-bromosulfone 3, undergo a smooth bromine–magnesium exchange with isopropylmagnesium bromide furnishing new functionalized organomagnesium species which react smoothly with various electrophiles like Me3SiCl, Bu3SnCl, allyl bromides, aldehydes, ketones or acid chlorides providing the expected products of type 7, 8 or 9.