Palladium(0)-Catalyzed Heteroarylation of 2- and 3-Indolylzinc Derivatives. An Efficient General Method for the Preparation of (2-Pyridyl)indoles and Their Application to Indole Alkaloid Synthesis
作者:Mercedes Amat、Sabine Hadida、Grigorii Pshenichnyi、Joan Bosch
DOI:10.1021/jo962169u
日期:1997.5.1
the pyridine ring with subsequent electrophilic cyclization upon the indole 3-position from an appropriately N(b)-substituted 2-(2-piperidyl)indole, is reported. For this purpose, Pummerer cyclizations have been extensively studied. Whereas the indole-unprotected sulfoxide 17 gives the corresponding indoloquinolizidine 19 in low yield and mainly undergoes an abnormal Pummerer cyclization that ultimately
钯(0)催化(1-(苯磺酰基)-2-吲哚基)氯化锌(1)和(1-(叔丁基二甲基甲硅烷基)-3-吲哚基)氯化锌(6)与不同取代的(烷基,甲氧基,甲氧基羰基,硝基,羟基)2-卤代吡啶以优异的产率得到相应的2-和3-(2-吡啶基)吲哚[分别为4和7(或8)]。由6类似地制备了一系列其他的3-(杂芳基)吲哚(吡嗪基,呋喃基,噻吩基,吲哚基)。证明了其中一些(2-吡啶基)吲哚在生物碱合成中的潜力。因此,从2-(2-吡啶基)吲哚4b开始,新合成吲哚[2,3-a]喹诺唑烷系统,涉及吡啶环的立体选择性氢化,随后在吲哚3-位从适当的位置进行亲电环化。报道了N(b)-取代的2-(2-哌啶基)吲哚。为此,已经对Pummerer环化进行了广泛的研究。吲哚未保护的亚砜17以低收率得到相应的吲哚并喹喔啉19,并且主要经历异常的Pummerer环化作用,最终导致硫化物18,而N(a)保护的亚砜24a和24b分别提供了7