Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine

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Abstract
A dual cycloaddition strategy for the synthesis of the hetisine alkaloids has been developed, illustrated by a concise asymmetric total synthesis of (+)‐nominine (7). The approach relies on an early‐stage intramolecular 1,3‐dipolar cycloaddition of a 4‐oxido‐isoquinolinium betaine dipole with an ene–nitrile dipolarophile. Subsequent late‐stage pyrrolidine‐induced dienamine isomerization/Diels–Alder cascade allows for rapid construction of the carbonnitrogen polycyclic skeleton within this class of C20‐diterpenoid alkaloids.