Biomimetic Total Syntheses of Clavine Alkaloids.

Biomimetic total syntheses of either enantiomers of a number of ergot alkaloids, chanoclavine I (1b), chanoclavine I aldehyde (1c), pyroclavine (1e), festuclavine (1f), pibocin A (1g), 9-deacetoxyfumigaclavine C (1h), and fumigaclavine G (1i), have been achieved from seco-agroclavine (1a). The advanced intermediate for seco-agroclavine (1a) was synthesized via a key thiourea-catalyzed intramolecular nitronate addition onto α,β-unsaturated ester.