A Total Synthesis of (±)-3-O-Demethylmacronine through Rearrangement of a Precursor Embodying the Haemanthidine Alkaloid Framework.

A total synthesis of the racemic modification, (±)-2, of the tazettine-type alkaloid 3-O-demethylmacronine is described. The key steps are an intramolecular Alder-ene (IMAE) reaction and a lactam-to-lactone rearrangement of tetracycle 13, a compound that embodies the haemanthidine alkaloid framework.