Basceken Sinan, Kaya Serdal, Balci Metin
Department of Chemistry, Middle East Technical University , 06800 Ankara, Turkey.
Department of Chemistry, Hitit University , 19030 Corum, Turkey.
J Org Chem. 2015 Dec 18;80(24):12552-61. doi: 10.1021/acs.joc.5b02419. Epub 2015 Dec 8.
Gold-catalyzed and NaH-supported intramolecular cyclization of N-propargyl indole derivatives with pyrazole and pyrrole units attached to indole is described. An efficient route to the synthesis of pyrazolodiazepinoindole, pyrazolopyrazinoindole, and pyrrolopyrazinoindole has been established. First, N-propargyl 2-(1H-pyrazol-5-yl)-1H-indole and 2-(1H-pyrrol-2-yl)-1H-indole were synthesized. Introduction of various substituents into the alkyne functionality was accomplished by Sonogashira cross-coupling reaction. Gold-catalyzed cyclization of pyrazoles having a terminal alkyne afforded the 6-exo-dig cyclization product. However, exclusive formation of 7-endo-dig cyclization products was observed with internal alkynes. On the other hand, cyclization with NaH only resulted in the formation of 6-exo-dig cyclization products regardless of the substitution of the alkyne functionality. Allenic intermediates were postulated for this outcome.
描述了金催化和氢化钠促进的、带有吡唑和吡咯单元的N-炔丙基吲哚衍生物的分子内环化反应。已建立了一条合成吡唑并二氮杂卓吲哚、吡唑并吡嗪吲哚和吡咯并吡嗪吲哚的有效路线。首先，合成了N-炔丙基-2-(1H-吡唑-5-基)-1H-吲哚和2-(1H-吡咯-2-基)-1H-吲哚。通过Sonogashira交叉偶联反应将各种取代基引入到炔烃官能团中。具有末端炔烃的吡唑的金催化环化反应得到6-外向-双环化产物。然而，对于内部炔烃，观察到仅生成7-内向-双环化产物。另一方面，无论炔烃官能团的取代情况如何，用氢化钠进行环化反应仅导致6-外向-双环化产物的形成。推测此结果是由联烯中间体导致的。
