posted on 2020-08-03, 14:39authored byCarlos Sedano, Rocío Velasco, Claudia Feberero, Samuel Suárez-Pantiga, Roberto Sanz
The α-lithiobenzyloxy
group, easily generated from aryl benzyl
ethers by selective α-lithiation with t-BuLi
at low temperature, behaves as a directed metalation group (DMG) providing
a direct access to o-lithiophenyl α-lithiobenzyl
ethers. This ortho-directing effect is reinforced
in substrates bearing an additional methoxy group at the meta position. The generated dianions can be reacted with a selection
of electrophiles including carboxylic esters and dihalosilanes or
germanes, which afford interesting benzofuran, sila(germa)dihydrobenzofuran,
and silachroman derivatives from simple aryl benzyl ethers.