使用由KO t Bu,BuLi和2,2,6,6,-四甲基哌啶(TMP(H ))。KO t的混合庚烷中的Bu,BuLi和TMP(H)给出了一种基础混合物的溶液,当用于氘标记实验时,证实了这三种试剂组分对反应性和选择性的要求。该反应方案在操作上简单明了,并且发现可适用于多种底物。在生成金属化产物时,它们在庚烷中于环境温度下以多种合成上有用的方式反应。所示实例包括苄基三甲基硅烷和α,α-双(三甲基甲硅烷基)甲苯试剂的产生,它们是用于亲核加成和彼得森烯化反应的苄基阴离子和α-甲硅烷基碳负离子的替身稳定替代物。由1,2-二溴乙烷介导的直接C-C偶联提供了联苄和[2.2]甲基环已烷的入口。
Homo- and Hetero-oxidative Coupling of Benzyl Anions
作者:Marco Blangetti、Patricia Fleming、Donal F. O’Shea
DOI:10.1021/jo3000805
日期:2012.3.16
The regioselective benzylic metalation of substituted toluenes using BuLi/KO-t-Bu/TMP(H) (LiNK metalation conditions) with subsequent in situ oxidative C-C coupling has been developed for the facile generation of 1,2-diarylethanes. A range of oxidants can be used for the oxidative coupling step, with 1,2-dibromoethane proving optimal. Heterocouplings can be achieved starting from a mixture of two different toluenes with a bias toward cross coupling achievable by using a 2-fold excess of one toluene starting material. The utility of this approach is illustrated by the synthesis of several biologically active natural products. A distinct advantage is that the synthetic steps typically required to preactivate the coupling substrates are eliminated and no transition metal is required to facilitate the C-C bond formation.