Bromine-magnesium exchange in gem-dibromocyclopropanes using Grignard reagents

Article abstract of DOI:10.1016/S0040-4020(02)00018-2

Reaction of gem-dibromocyclopropanes with ethylmagnesium bromide at ambient temperature leads to very high yields of allenes; when cyclopropylidene-allene ring opening is suppressed, alternative carbenic products are observed, although other reactions compete. When the reactions are carried out at -60°C, a 1-bromo-1-(bromomagnesio)-cyclopropane is formed which may be trapped by a number of electrophiles.