Lithiation of Aryl Bromides Possessing α-Proton of Carbonyl Groups
作者:Yuhei Yamamoto、Kenji Maeda、Koji Tomimoto、Toshiaki Mase
DOI:10.1055/s-2002-22727
日期:——
A new methodology for metalation of aryl bromide possessing an active methylene adjacent to carbonyl groups is described. In order to avoid self-quenching, selective deprotonation was necessary prior to halogen-metal exchange reaction. For this purpose, mesityllithium was found to be the best choice. Subsequent treatment with n-BuLi resulted in the lithium-bromine exchange to generate the dianion,
Depending on the N-heterocyclic carbene catalyst utilized, alpha-unbranched aldehydes selectively provided amides, esters, or carboxylicacids through oxidation by NCS. The alpha-unbranched aldehyde underwent these reactions chemoselectively in the presence of an aromatic or alpha-branched aldehyde.