Ingestion of alkaloid metabolites from the bark of Galbulimima (GB) sp. results in psychotropic and excitatory results in people1–4. Restricted, variable provide of GB alkaloids1, nevertheless, has impeded their organic exploration and scientific improvement2. Right here we report an answer to the availability of GB18, a structural outlier and putative psychotropic precept of Galbulimima bark. Environment friendly entry to its difficult tetrahedral attached-ring motif required the event of a ligand-controlled endo-selective cross-electrophile coupling and a diastereoselective hydrogenation of a rotationally-dynamic pyridine. Dependable, gram-scale entry to GB18 allowed its project as a potent antagonist of kappa– and mu– opioid receptors—the primary new targets in 35 years—and lay the muse to navigate and perceive the organic exercise of Galbulimima metabolites.