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Published on: January 19, 2016
Metal-Free Cyclization of ortho-Nitroaryl Ynamides and Ynamines towards Spiropseudoindoxyls
Niels Marien1, B Narendraprasad Reddy1, Freija De Vleeschouwer2
1Research Group of Organic Chemistry (ORGC), Department of Chemistry and Department of Bio-engineering Sciences, Faculty of Science and Bio-engineering Sciences, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050, Brussels, Belgium.
Abstract:
An efficient metal-free cascade reaction between 1-dibromovinyl-2-nitro-substituted arenes and secondary amines results in the formation of polycyclic pseudoindoxyls in a single step. The reaction mechanism leading to these fused ring systems was investigated, and is believed to involve the initial formation of nitroarylated ynamines/ynamides. These intermediates cycloisomerize towards N-alkenyl-tethered 2-aminoisatogens via a carbene intermediate as demonstrated by QTAIM (quantum theory of atoms in molecules) and ELF (electron localization function) analysis. A subsequent intramolecular dipolar cycloaddition afforded the title compounds.
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