α-Lithiobenzyloxy as a Directed Metalation Group in <i>ortho</i>-Lithiation Reactions
作者:Carlos Sedano、Rocío Velasco、Claudia Feberero、Samuel Suárez-Pantiga、Roberto Sanz
DOI:10.1021/acs.orglett.0c02199
日期:2020.8.21
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
α-硫代苄氧基很容易通过在低温下用t -BuLi选择性地进行α-锂化反应而从芳基苄基醚生成,其表现为定向金属化基团(DMG),可直接与邻-硫代苯基α-硫代苄基醚接触。这种邻位导向作用在在间位带有额外甲氧基的底物中得到增强。生成的二价阴离子可与包括羧酸酯和二卤硅烷或锗烷在内的各种亲电试剂反应,这些亲电试剂可从简单的芳基苄基醚制得令人感兴趣的苯并呋喃,硅烷基(锗)二氢苯并呋喃和硅铬烷衍生物。