A cyclization of alk-4-ynals with aliphatic diamines in DMSO upon treatment with KOH was found to lead to bicyclic N,N-enaminals. The studies of this reaction showed that 1,3-diaminopropane and N-methyl-1,3-diaminopropane gave (E)-6-(arylmethylidene)octahydropyrrolo[1,2-a]pyrimidines in 45—78% yields, whereas 1,2-diaminoethane gave 5-(arylmethylidene)hexahydropyrrolo[1,2-a]imidazoles as mixtures of E- and Z-isomers in up to 75% total yield. The mechanism of these new cascade cyclization reactions includes formation of the equilibrium mixtures of imines and cyclic aminals with subsequent intramolecular hydroamination of the triple bond having considerable ionic character.
在KOH处理下,将烷-4-炔醛与脂肪族二胺在
DMSO中进行环化反应,可得到双环N,N-烯胺醛。研究表明,1,3-二
氨基
丙烷和
N-甲基-1,3-二
氨基
丙烷分别以45—78%的产率生成(E)-6-(芳
甲叉基)八氢
吡咯并[1,2-a]
嘧啶,而1,2-二
氨基
乙烷则以高达75%的总产率生成5-(芳
甲叉基)六氢
吡咯并[1,2-a]
咪唑的E型和Z型异构体混合物。这些新型串联环化反应的机理包括形成
亚胺和环状二胺的平衡混合物,随后发生具有显著离子特性的三键分子内
氢胺化反应。