Regio- and Stereoselective Electrophilic Cyclization Approach for the Protecting-Group-Free Synthesis of Alkaloids Lennoxamine, Chilenine, Fumaridine, 8‑Oxypseudoplamatine, and 2‑O‑(Methyloxy)fagaronine

A unified strategy for protecting-group-free synthesis of alkaloids lennoxamine, chilenine, fumaridine, 8-oxypseudoplamatine, and 2-O-(methyloxy)­fagaronine is reported. The core isoindolin-1-one and isoquinolin-1-one structures were built by a silver-catalyzed regio- and stereoselective cyclization of methyl 2-alkynylbenzimidates. The regioselectivity of cyclization was achieved by utilizing the intrinsic functionality of alkaloids.