Synthesis of Antitumor Lycorines by Intramolecular Diels-Alder Reaction.
Pharmacologically interesting lycorines were obtained by a short, efficient method based on an intramolecular Diels-Alder reaction between an alpha-pyrone and an alkyne, followed by loss of CO(2) in a retro Diels-Alder reaction. The cyclization precursors (pyrones 9) were obtained in good yields in two or three steps from the corresponding homophthalic acid or anhydride.
Pérez
Dolores
D
Departamento de Química Orgánica, Universidad de Santiago, and Sección de Alcaloides del CSIC, 15706 Santiago de Compostela, Spain.
Burés
Gema
G
Guitián
Enrique
E
Castedo
Luis
L