Total synthesis of strychnan and aspidospermatan alkaloids. 3. The total synthesis of (.+-.)-strychnine

Reaction of N b -benzyl-2-[(methoxycarbonyl)methyl]tryptamine (3) with 4,4-dimethoxybut-2-en-1-el (6) provided, by a new condensation-electrocyclization reaction, the tetracyclic core pyrrolo[2,3-d]carbazole derivative (2) of strychnine (1). A 13-step elaboration of this compound gave a stereoselective synthesis of the racemic alkaloid