A potent
dopamine (D2) receptor agonist (±)-
quinagolide, which is used for the treatment of
hyperprolactinemia, was synthesized using the ring closing metathesis (RCM) approach from
meta-hydroxybenzaldehyde as the starting material. The key features of this synthesis are pyrolytic elimination, late-stage expedient synthesis of functionalized trans-fused tetrahydropyridine-3-carboxylates from
olefin 6, via conjugate addition-elimination upon
acetate 11, followed by RCM and phenyliodine bis(
trifluoroacetate) (PIFA)-mediated Hofmann rearrangement of piperidine-3-carboxamide, which enables the synthesis of 3-aminopiperidine skeleton of
quinagolide. For the total synthesis of natural products such as
ergot alkaloids, late-stage synthesis of functionalized trans-fused tetrahydropyridine-3-carboxylates using RCM and PIFA-mediated Hofmann rearrangement of piperidine-3-carboxamide, which allows quick access to the synthetically challenging 3-aminopiperidine skeleton, are the main achievements of the present work.