In considering strategies to achieve these goals, we recognised that two approaches might afford access to the Strychnos core (Fig. ). We first envisaged that tryptamine (1) could undergo alkylation with a sidechain (2) suitable for downstream completion of the targeted natural products, and then an addition-elimination (substitution) reaction with a halogenated thiophene S,S-dioxide 3 to give intermediate 4. This TDO would react with the tethered indole via a stereoselective intramolecular IEDDA / SO2 cheletropic extrusion pathway to form tetracycle 5 after reduction of the intermediate cycloadduct, further functionalisation of which would afford the Strychnos natural products.