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Total Synthesis of (±)-Lysergic Acid
Total Synthesis of (±)-Lysergic Acid by an Intramolecular Imino-Diels–Alder Reaction.
Helv. Chim. Acta 1981;
Key wordslysergic acid - Diels–Alder reaction - Appel reaction - Nef reaction - Wittig olefination - Mannich reaction - ergoline alkaloids
In 1981, Oppolzer and co-workers reported a concise synthesis of (±)-lysergic acid, a precursor for many ergoline alkaloids. Their synthesis improved upon earlier approaches in terms of efficiency and length by utilizing a Diels–Alder cycloaddition as the key step.
Intermediate F was accessed from 4-hydroxymethyl-1-tosylindole (A) in four steps and was converted to J either directly by treatment with G, or more efficiently over two steps. Nef reaction gave rise to K, which underwent retro-Diels–Alder followed by Diels–Alder cycloaddition in one pot at 200 °C. Three more steps gave (±)-lysergic acid.
16 December 2020 (online)
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