Sulfoxides are known to be powerful directing groups for ortho-lithiation, even in competition with other directors. This has been utilised to introduce substituents meta- to a methoxy-group by sequential lithiation, reaction with Me tert-butylsulfinate, and a second lithiation. Electrophilic trapping of the ensuing lithio-compound with a range of electrophiles followed by reductive removal of the sulfoxide led to meta-substituted anisoles. Some interesting side-reactions were uncovered, including a short synthesis of quinazolines arising from the use of PhCN in the second step.
众所周知,
硫醚是正置
石灰化反应的强力引导基团,甚至可以与其他引导基团竞争。我们利用这种方法,通过连续的
石灰化反应、与 Me tert-butylsulfinate 反应和第二次
石灰化反应,将取代基 meta 引入甲氧基。随后,用一系列亲电物对石
硫化合物进行亲电捕获,然后还原去除亚砜,从而得到元取代的
苯甲醚。还发现了一些有趣的副反应,包括在第二步中使用 PhCN 而产生的
喹唑啉类化合物的简短合成。