One-pot generation of lithium (lithiophenyl)trialkoxyborates from substituted dihalobenzenes (Hal = Br, I) and their derivatization with electrophiles

The simple one-pot approach to synthetically useful phenyl-trialkoxyborates bearing lithium at the phenyl ring has been developed starting with 1,3- and 1,4-diiodobenzene, as well as several activated dibromobenzenes and bromoiodobenzenes. The general sequence of transformations involves halogen-lithium exchange by using nBuLi and subsequent boronation with a trialkylborate. The resulting lithium (halophenyl)trialkoxyborates were then subjected to halogen-lithium exchange in situ with a second equivalent of nBuLi to give dianionic lithium (lithiophenyl) trialkoxyborates. Treatment with selected electrophiles afforded substituted arylboronic acids and/or their pinacol esters as final products in moderate-to-good yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).