67. Total Synthesis of (±)-Lysergic Acid by an Intramolecular Imino-Diels-Alder Reaction. Preliminary communication
    Oppolzer, W.; Francotte, E.; Bättig, K.
    Helv. Chim. Acta 1981, 64, 478-481

(±)-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.

DOI : 10.1002/hlca.19810640212