Total Synthesis of (±)‐Haliclonacyclamine C

First in its class: The synthesis of the tetracyclic alkylpiperidine marine alkaloid (±)-haliclonacyclamine C has been completed, with a longest linear sequence of 24 steps. The key transformations are the stereoselective hydrogenation of an unsaturated macrocyclic bis(piperidine) and a ring-closing alkyne metathesis reaction.