A Total Synthesis of (±)-3‑<i>O</i>‑Demethylmacronine through Rearrangement of a Precursor Embodying the Haemanthidine Alkaloid Framework

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