A stereospecific anionic reduction of gem-bromohalocyclopropanes by the dimsyl anion

Article abstract of DOI:10.1002/recl.19941130108

The reaction of several 2,2,3,3-tetrasubstituted-gem-bromohalocyclopropanes with t-BuOK in DMSO unexpectedly yielded the monohalocyclopropanes in good yield.A closer investigation revealed that this reaction must be initiated by a nucleophilic attack by the dimsyl anion (CH3SOCH2(1-)) on bromine with subsequent protonation of the carbenoid intermediate.The reaction occurs rapidly (within 2 minutes) and is not inhibited by radical scavengers or in the dark.Only bromine, and not chlorine, is reduced, and the intermediate cyclopropyl anion is configurationally stable under the reaction conditions.