Simple and Convenient Synthesis of Iboga-Functionalized Isoquinuclidines

Synthesis of Iboga-functionalized isoquinuclidine ring system and alkylated derivatives from commercially available 3-ethyl-pyridine, is reported. The key-step for isoquinuclidine synthesis is a cycloaddition between methyl acrylate and N-benzyl-3- ethyl-5,6-dihydropyridine obtained in situ from N-benzyl-3-ethyl-4-methoxy-1,4,5,6- tetrahydropyridine. Further treatment of isoquinuclidine lithium enolate with appropriate electrophiles gave alkylated products with good stereoselectivity.