The key reaction in the Vollhardt synthesis (2000, racemic) was an alkyne trimerisation of tryptamine derivative 1 with acetylene and organocobalt compound CpCo(CH) (THF, 0 °C) to tricycle 2 after deprotection of the amine group (KOH, MeOH/HO reflux). Subsequent reaction with iron nitrate brought about a [1,8]-conjugate addition to tetracycle 3, amine alkylation with (Z)-1-bromo-4-[(tert-butyldimethylsilyl)oxy]-2-iodobut-2-ene (see Rawal synthesis) and lithium carbonate, and isomerization of the diene system (NaOiPr, iPrOH) formed enone 4. A Heck reaction as in the Rawal synthesis (palladium acetate / triphenylphosphine), accompanied by aromatization formed pyridone 5 and lithium aluminium hydride reduction and TBS group deprotection formed isostrychnine 6.