Total synthesis of ht-13-A and ht-13-B, total synthesis of aurantioclavine, progress towards the synthesis of cycloclavine

Total synthesis of tetracyclic indole alkaloid ht-13-A and ht-13-B has been accomplished from commercially available (S)-4-amino-2-hydroxybutyric acid and trans- 4-hydroxy-L-proline respectively. The key synthetic steps include an acyliminium ion allylation, a Mitsunobu reaction, a palladium-catalyzed Stille-Kelly cross coupling reaction, and a carbon monoxide mediated palladium-catalyzed reductive Nheterocyclization. The total synthesis of aurantioclavine has been studied. The synthesis commenced with 2-amino-3-nitrophenol. Key synthetic steps include a Stille coupling reaction, a Heck reaction, a Lewis acid mediated cyclization and a carbon monoxide mediated palladium-catalyzed reductive N-heterocyclization. In addition, the first asymmetric total synthesis of (+)-cycloclavine has been studied. Key synthetic steps include a ring closing metathesis, an acyliminium ion allylation and a Stille coupling.