Enantioselective Total Synthesis of (-)- Lansai B and (+)- Nocardioazines A and B

The concise total syntheses of the bis(pyrroloindolines) (-)- lansai B and (+)- nocardioazines A and B are reported. The key pyrroloindoline building blocks are rapidly prepared by enantioselective formal [3+2] cycloaddition reactions. The macrocycle of (+)- nocardioazine A is constructed by an unusual intramolecular diketopiperazine formation.