Obtention de cyclopropanes gem-dicarboxylate par cyclocondensation de carbanions bromo- et chloromalonate sur des accepteurs de Michaël

Cyclopropane gem-dicarboxylates are prepared through cyclocondensation of chloro or bromomalonate carbanion and electrophilic alkenes. The carbanion can be formed in THF by deprotonation of the monohalomalonates with powdered potassium carbonate; the chloromalonate always leads to better yields. The influence of the nature and the number of substituents on the alkene reactivity has been investigated. If side reactions (for instance protonation of anionic intermediates by halomalonate) can take place, better yields are obtained when the carbanion is generated by electroreduction of dihalomalonate in the presence of the Michael acceptor. Key words: halomalonates, cyclopropane gem-dicarboxylates, electroreduction.