Total synthesis of the tetracyclic indole alkaloid ht-13-A

• Published in: Tetrahedron letters Vol. 57; no. 26; pp. 2865 - 2867
• Main Authors: Zhang, Yilin, McArdle, Ian W., Hubbard, Jeremiah W., Akhmedov, Novruz G., Söderberg, Björn C.G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29-06-2016
• Subjects: ht-13-A; Palladium catalyzed; Reductive cyclization; Total synthesis; Palladium catalyzed; Reductive cyclization; ht-13-A; Total synthesis
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2016.05.060

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•Synthesis of the tricyclic indole alkaloid ht-13-A has been completed.•4-Amino-2(S)-hydroxybutyric acid served as the ultimate source of the two chiral centers seen in ht-13-A.•The correct chirality was obtained via a Mitsunobu reaction and a Lewis acid mediated acyliminium allylation.•Two palladium catalyzed reactions, a Stille-Kelly reaction, and a reductive N-heterocyclization were used as key ring-closing steps.
Total synthesis of the tetracyclic indole alkaloid ht-13-A is reported starting ultimately from commercially available (−)-4-amino-2-hydroxybutyric acid. The key steps in this synthesis are a Lewis acid mediated acyliminium ion allylation, a Mitsunobu reaction, a palladium catalyzed Stille-Kelly intramolecular cross coupling, and a carbon monoxide mediated palladium catalyzed reductive N-heterocyclization.