A copper-promoted C3-cyanation of both the free N–H and N-protected indoles by N,N,N′,N′-tetramethyl-ethane-1,2-diamine (TMEDA) and ammonium is achieved. The iminium ion acts as the intermediate in this transformation, which is sequentially electrophilically attacked by indole and H2O followed by hydrolyzation to form the aldehyde. Then the reaction between the aldehyde and ammonium afforded nitriles. The reaction employs O2 as a clean oxidant with good efficiency and functional group tolerance. Thus, it represents a facile and safe procedure leading to 3-cyano indoles.
通过 N,N,N′,N′-四甲基
乙烷-1,2-二胺(TME
DA)和
铵的促进,
铜催化的 C3-
氰化反应成功实现了游离 N–H 和 N-保护
吲哚的
氰化。
亚胺离子作为该转化过程中的中间体,依次受到
吲哚和
H2O 的亲电攻击,然后
水解形成醛。接着,醛与
铵的反应生成腈。这一反应采用 O2 作为清洁氧化剂,具有良好的效率和官能团耐受性。因此,它代表了一种简便且安全的步骤,能够产生 3-
氰吲哚。