Total Synthesis of Phenanthropiperidine Alkaloids by Sequential Alkylation of <i>N</i> , <i>N</i> ‐Dibenzylaminoacetonitrile

Two representative members of the phenanthropiperidine alkaloid family, tylophorine (1) and cryptopleurine (2), were synthesized by a bidirectional alkylation strategy employing dibenzylaminoacetonitrile as substrate. This approach relies on unprecedented condensation metallated α-aminonitriles with bromomethylphenanthrenes to provide fully substituted α-aminonitriles, which are subjected NaBH4-mediated reductive decyanation process form homobenzylic amines. From these intermediates, terminal leaving group was introduced simple chemical manipulation, its displacement free primary amine under two favorable cyclization processes led formation future E-ring both alkaloids in high yields. Finally, late Pictet-Spengler ensured D-ring for 1 2.