The efficiency of the intramolecular carbonickelation of substituted allylic ethers and amines has been studied to evaluate the influence of the groups borne by the double bond on this cyclization. The results show that when this reaction takes place, it affords only the 5-exo-trig cyclization products, viz. dihydrobenzofurans or indoles. Depending on the tethered heteroatom (O or N), the outcome of the cyclization differs. While allylic ethers are relatively poor substrates that undergo a side elimination and need an intracyclic double bond to proceed, allylic amines react well and afford indoline and indole derivatives. Finally, the synthesis of the trinuclear ACE core of a morphine-like skeleton was achieved by using NiBr2bipy catalysis.
取代
烯丙基醚和胺的分子内碳
镍化效率已经研究,以评估双键上的基团对这种环化反应的影响。结果显示,当这种反应发生时,只产生5-
exo-trig环化产物,即二氢
苯并呋喃或
吲哚。取决于连接的杂原子(O或N),环化的结果不同。虽然
烯丙基醚是相对较差的底物,会发生侧链消除并需要一个分子内双键来进行,
烯丙基胺反应良好,并产生
吲哚啉和
吲哚衍
生物。最后,通过使用NiBr
2bipy催化剂实现了类似
吗啡骨架的三核ACE核心的合成。