Total Synthesis of (±)‐Lysergic Acid by an Intramolecular Imino‐<i>Diels</i>‐<i>Alder</i> Reaction. Preliminary communication

Abstract

Abstract (±)‐Lysergic acid ( 1 ) has been synthesized from 4‐hydroxymethyl‐1‐tosylindole ( 2 ) by a sequence of 9 steps. The crucial thermolysis 9 → 10 involves the in situ ‐generation of the transient diene III which undergoes an intramolecular cycloaddition to a C, N‐double bond at 200° and at low stationary concentration of III.