Bromine–magnesium exchange in gem-dibromocyclopropanes using Grignard reagents
摘要:
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 -60degreesC, a 1-bromo-1-(bromomagnesio)-cyclopropane is formed which may be trapped by a number of electrophiles. (C) 2002 Elsevier Science Ltd. All rights reserved.