Total synthesis of Amaryllidaceae alkaloids utilizing sequential intramolecular heterocyclic azadiene Diels-Alder reactions of an unsymmetrical 1, 2, 4, 5-tetrazine
... Total Synthesis of Anhydrolycorinone, Anhydrolycorinium Chloride, and Hippadine. 2-Bromopiperonal was protected as its diethyl ketal [HC(OEt) 3 , p-TsOH, EtOH, 80 °C, 24 h] and converted to the known aldehyde 7 11 via lithium−halogen exchange (n-BuLi, Et 2 O, −30 °C, ...