1,2,2-tribromocyclopropanecarboxylic acid and derivatives - Valuable intermediates for four carbon cyclopropane and cyclopropene synthons

Methyl 1,1,2-tribromocyclopropanecarboxylate is readily available by dibromocyclopropanation of methyl alpha-bromoacrylate. Reaction with methyllithium at low temperature provides a simple route to methyl 2-bromocyclopropene carboxylate. while modification of the ester group followed by reaction with methyllithium leads to a series of related four-carbon cyclopropenes. The tribromo-ester is also readily converted into 1,1,2,2-tetrabromocyclopropane, a valuable three-carbon cyclopropene synthon.