A DIASTEREOSELECTIVE SILVER(I)PROMOTED GEM-DIBROMOCYCLOPROPANE RING OPENING REACTION VIA AN ANCHIMERIC ASSISTED TRANSANNULAR BENZOATE MIGRATION

摘要

A highly diastereoselective synthesis of a protected 4-amino-5,7-dihydroxy-1-bromocyclohept-1-ene was achieved by a silver tosylate promoted gem-dibromocyclopropane ring opening reaction.The target molecule was prepared in only six steps from benzene or four steps from 7,7-dibromo-3-norcarene.The key to this approach was the discovery of a stereoselective transannular benzoate migration,which occurred via tandem anchimeric assistance in a silver(I)promoted gem-dibromocyclopropane ring opening reaction.