Bioinspired Formal Synthesis of Pancracine Via Selective Hydro­genation of an Indole Derivative

A bioinspired formal synthesis of the montanine-type Amaryllidaceae alkaloid pancracine through selective hydrogenation of a 3-arylindole derivative is disclosed. The key features of this synthesis include a hexahydroindole synthesis by a chemoselective hydrogenation of an aryl-substituted indole and a diastereoselective silyl hydride reduction of an iminium intermediate generated from an enaminone through Tf2O activation. The eight-step assembly of the 5,11-methanomorphanthridine framework represents a novel and efficient strategy that permits one of the shortest syntheses of pancracine reported so far.