[4 + 2] cycloadditions of N-alkenyl iminium ions: structurally complex heterocycles from a three-component
Nihar Sarkar1, Abhisek Banerjee, Scott G Nelson
1University of Pittsburgh Center for Chemical Methodologies and Library Development, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Abstract:
N-Alkenyl iminium ions serve as conduits to three-component [4 + 2] cycloaddition reactions accessing structurally and stereochemically diverse piperidine derivatives. These cationic 2-azadienes participate in endo- or exo-selective [4 + 2] cycloadditions with electron-rich and neutral alkene dienophiles to generate a tetrahydropyridinium ion as the initial cycloadduct. In situ nucleophilic addition to the cycloaddition-derived iminium ion completes the three-component coupling sequence and affords a versatile synthesis of structurally complex piperidines.
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