Bis(ether) derivatives of tetrakis(2-hydroxyphenyl)ethene - Direct synthesis of (E)- and (Z)-bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene via the McMurry olefination reaction

摘要

The direct synthesis of sterically hindered,partially etherified derivatives of tetrakis(2-hydroxyphenyl)ethene is reported by using the McMurry reductive olefination reaction on a range of differentially substituted 2,2'-dialkoxy-benzophenone substrates.Three orthogonal protection strategies are demonstrated,incorporating beta-silylethyl,3-butenyl,and tert-butyl protecting groups,respectively,into the starting benzophenones.The latter proved most efficient,with both the McMurry coupling and deprotection steps occurring concomitantly under the McMurry conditions to directly yield the desired bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene as a 1:1 mixture of E- and Z-diastereoisomers.