Total Syntheses of 2,2' -Biindolyl Alkaloids via Cyanide-Catalyzed Imino-Stetter Reaction

2,2'-Biindolyl natural products have a long history of applications owing to their unique structural features and biological activities. In this Account, we describe the recent progress achieved by our research group in the total syntheses of several 2,2'-biindolyl natural products using the cyanide-catalyzed imino-Stetter reaction as the key reaction to construct the 2,2'-biindolyl scaffold from 2-aminocinnamic acid derivatives and indole-2-carboxaldehydes. The development of a novel protocol to access 2,2'-bisindole-3-acetic acid derivatives via the cyanide-catalyzed imino-Stetter reaction and its application to the total syntheses of class I (arcyriaflavin A), class II (iheyamines A and B), and class III (calothrixin B) 2,2'-biindolyl natural products are discussed.1. Introduction2. Synthesis of 2,2'-Biindolyl Compounds via Cyanide-Catalyzed Imino-Stetter Reaction3. Total Synthesis of Arcyriaflavin A4. Total Syntheses of Iheyamines A and B5. Total Synthesis of Calothrixin B6. Conclusion