Autocatalytic Double sigma-Bond C(sp2)–N Transamination Metathesis Reaction

The transamination reaction, which involves the conversion of one amine to another, traditionally relies on biological enzyme catalysts. Although chemists have recently developed few catalytic methods, mimicking these enzymes to interconvert amine groups in acyclic substrates via transamination metathesis of a single C(sp2)–N bond, transamination of cyclic tertiary amines has remained a long-standing unsolved problem in synthetic chemistry. Here, we present an unprecedented autocatalytic transamination metathesis of two C(sp2)–N bonds in a cyclic substrate that allows for the challenging transformation to take place under exceptionally mild and environmentally friendly reaction conditions. The methodology gives rapid and atom economical access to N-substituted 1,4-dihydropyridines (1,4-DHPs), which are privileged structures in bioactive compounds, pharmaceuticals and photoelectronic functional materials.