o-Cyanobenzyllithium (3) was efficiently generated by lithium-tellurium exchange of the corresponding benzylic telluride 2 prepared in situ from lithium butanetellurolate and α-bromo-o-tolunitrile (1). Reaction of ketones or aldehydes with 3 afford substituted 2-hydroxyethylbenzonitriles 4 in high yields. The subsequent acid-catalyzed lactonization gave 3-substituted 3,4-dihydroisocoumarins 5 in good yields. All these successive reactions could be performed in the same reaction flask without isolation of intermediates.
通过
锂碲交换反应,从丁基
碲醇
锂和α-
溴邻
甲苯腈(1)原位合成的苄位
碲化物(2)高效生成了邻
氰苄基
锂(3)。酮或醛与(3)反应,以高产率得到取代的2-羟基乙基
苯甲腈(4)。随后的酸催化内酯化反应以良好产率得到3-取代的3,4-二氢异
香豆素(5)。所有这些连续反应都可以在同一个反应瓶中进行,无需分离中间体。