One‐Pot Generation of Lithium (Lithiophenyl)trialkoxyborates from Substituted Dihalobenzenes (Hal = Br, I) and Their Derivatization with Electrophiles

Abstract

Abstract The simple one‐pot approach to synthetically useful phenyltrialkoxyborates 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 n BuLi 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 n BuLi 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)