Functionalization of Dihalophenylboronic Acids by Deprotonation of Their N-Butyldiethanolamine Esters

Deprotonative lithiation of various 6‐butyl‐2‐(dihalophenyl)‐(N–B)‐1,3,6,2‐dioxazaborocanes (N‐butyldiethanolamine esters of dihalophenylboronic acids) was investigated. It was found that selective transformations can be best achieved by use of LDA as the lithiating reagent. The reactivities of these compounds vary significantly, depending on the natures and positions of the halogen atoms. The resultant boron‐lithium bimetallic intermediates were subjected to reactions with electrophiles to afford functionalized halogenated arylboronic acids. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) Protected halogenated arylboronic acids were subjected to deprotonation with lithium amide bases to form bimetallic boron‐lithium intermediates, which were subsequently treated with electrophiles to give functionalized arylboronic acids.