Synlett 2004(4): 577-595  
DOI: 10.1055/s-2004-817767
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

Total Synthesis of Ciguatoxin CTX3C, a Causative Toxin of Ciguatera Seafood Poisoning

Masayuki Inoue*, Masahiro Hirama*
Department of Chemistry, Graduate School of Science, Tohoku University, and SORST, Japan Science and Technology Agency (JST), Sendai 980-8578, Japan
Fax: +81(22)2176566; e-Mail: inoue@ykbsc.chem.tohoku.ac.jp; e-Mail: hirama@ykbsc.chem.tohoku.ac.jp;
Further Information

Publication History

Received 1 September 2003
Publication Date:
10 February 2004 (online)

Abstract

More than 20,000 people suffer annually from ciguatera seafood poisoning in subtropical and tropical regions. The extremely low content of the causative neurotoxins, designated as cigua­toxins, in fish has hampered the isolation, detailed biological studies, and preparation of anti-ciguatoxin antibodies for detecting these toxins. Furthermore, the large (3 nanometer long) and complicated molecular structure of ciguatoxins has impeded chemists from completing their total synthesis. In 2001, our highly convergent strategic approach enabled the total synthesis of ciguatoxin CTX3C through assembling the four structural fragments. In this account, we describe the updated version of the total synthesis, where the yields and practicality are greatly improved. The high efficiency of the present synthesis ensures a supply of ciguatoxins for biomedical applications.

30

The numbering of carbon atoms in all compounds in this paper corresponds to that of CTX3C.

36

Compound 24 was independently synthesized in the same way by Perlmutter and co-workers (ref. 19j).

67

See ref. 65. The authors noted that the cleavage of a seven-membered acetal proceeded more easily than a six-membered acetal in a Lewis acid-catalyzed intramolecular condensation of a γ-alkoxyallylsilane.

74

Deprotection of Bn group under Birch conditions were applied to the AB ring system 24 to afford the desired compound 25 in much better yield (>59%, Scheme [2] ), which again support the distinct reactivity of the nano-scale molecule 140