One-Pot Synthesis of Isoquinuclidines via 2,6-Diaryl-1,2-dihydropyridines using (E,E)-Cinnamylideneacetophenones as Templates

Diastereoselective Diels–Alder reactions of 2,6-diaryl-1,2-dihydropyridines with N-methylmaleimide afford highly substituted isoquinuclidines in good chemical yield (30–50%). This sequential one-pot synthesis is performed under microwave irradiation and involves, primarily, the synthesis of 2,6-diaryl-1,2-dihydropyridines by a 6π-azaelectrocyclisation involving an intermediate α,β,γ,δ-di-unsaturated imine, obtained by condensation of (E,E)-cinnamylideneacetophenones with amines. This procedure easily converts unstable 2,6-diaryl-1,2-dihydropyridines into, otherwise inaccessible, isoquinuclidines without any kind of manipulation.