On the Validity of Au-vinylidenes in the Gold-Catalyzed 1,2-Migratory Cycloisomerization of Skipped Propargylpyridines
摘要:
A mechanism of the Au-catalyzed cycloisomerization of propargylpyridines has been investigated. Both DFT computational and experimental results strongly support generation of a Au-carbene via a cyclization/proton transfer sequence over the previously proposed path involving a Au-vinylidene intermediate. For the beta-Si-substituted Au-carbene (G = SiR3), a 1,2-Si migration was shown to be kinetically favored over a 1,2-H shift. This study highlights the importance of alternative pathways that could explain reactivities commonly attributed to an alkyne-vinylidene isomerization in Au catalysis.
已开发出一种在 Au 催化剂存在下从各种炔丙基取代的杂环合成稠合吡咯杂环的有效方法。级联转化通过炔烃-亚乙烯基异构化进行,伴随着氢、甲硅烷基和甲硅烷基的 1,2-位移。值得注意的是,还表明,在这些反应条件下,炔-亚乙烯基重排发生了以前未知的锗烷基的 1,2-迁移。这种方法可以温和有效地合成各种 C-2 取代的含 N 杂环。
Multisubstituted N-fused heterocycles via transition metal-catalyzed cycloisomerization protocols
作者:Ilya V. Seregin、Alex W. Schammel、Vladimir Gevorgyan
DOI:10.1016/j.tet.2008.04.023
日期:2008.7
multisubstituted N-fused heterocycles have been developed. It was demonstrated that 1,3-disubstituted N-fused heterocycles, including indolizines, pyrroloquinoxalines, and pyrrolothiazoles can easily be synthesized via an exceptionally mild and efficient method involving a novel silver-catalyzed cycloizomerization of propargyl-containing heterocycles. Alternatively, 1,2-disubstitutedheterocycles can be accessed