Pyrrole versus quinoline formation in the palladium catalyzed reaction of 2-alkynyl-3-bromothiophenes and 2-alkynyl-3-bromofurans with anilines. A combined experimental and computational study
作者:Ghazwan Ali Salman、Riffat Un Nisa、Viktor O. Iaroshenko、Jamshed Iqbal、Khurshid Ayub、Peter Langer
DOI:10.1039/c2ob26689j
日期:——
3-dibromothiophene was employed as the starting material. In the present article, a detailed DFT study related to the mechanism (quinoline versus pyrrole formation) is reported which provides a rationalization of the selectivities observed for the furan, benzofuran, thiophene and benzothiophene series and for the different selectivities observed for electron-rich and -poor anilines.
苯并呋喃喹啉是通过新型的Pd催化环化反应制备的。第一步,通过2,3-二溴苯并呋喃的Sonogashira反应制备2-炔基-3-溴苯并呋喃。通过多米诺骨牌C–N偶联/环化过程,他们的Pd催化与富电子苯胺的反应提供了苯并呋喃喹啉。该反应通过苯胺的氮原子和邻碳以C,N-环化的方式进行。类似地,从2,3-二溴呋喃制备呋喃喹啉。相反,苯并呋喃并吡咯由N,N形成。使用弱电子苯胺时的环化反应。之前,我们报道了与噻吩和苯并噻吩系列有关的结果。当使用富含电子的苯胺时,由2,3-二溴苯并噻吩形成喹啉。相反,在电子贫乏的苯胺的情况下获得吡咯。另一方面,当将2,3-二溴噻吩用作起始原料时,通常不依赖于苯胺的类型而获得吡咯。在本文中,报道了与该机理相关的详细DFT研究(喹啉与吡咯的形成),该研究合理化了呋喃,苯并呋喃,噻吩和苯并噻吩系列的选择性,以及富电子和氟代苯的不同选择性。 -苯胺少。