Convergent Synthesis of the E‘FGH Ring Fragment of Ciguatoxin 1B via an Acetylene Cobalt Complex Strategy
- 18 March 2003
- journal article
- Published by American Chemical Society (ACS) in The Journal of Organic Chemistry
- Vol. 68 (8), 3225-3231
- https://doi.org/10.1021/jo034021y
Abstract
A convergent synthesis of the E'FGH ring fragment 28 of ciguatoxin 1B, a principal toxin causing widespread seafood poisonings "ciguatera", has been accomplished through (i) coupling between the E' ring-acetylide 9 and the H ring-aldehyde 20, (ii) stereoselective F ring cyclization via an acetylene cobalt complex, (iii) conversion to a carbonyl function under high-pressure hydrogenation, and (iv) reductive hydroxyketone cyclization to construct the G ring. In the (1)H NMR analysis of 28 at room temperature, a considerable broadening phenomenon was observed due to the slow conformational changes of the FG ring, as reported for natural ciguatoxin 1B. When measured in pyridine at -20 degrees C, the spectra of 28 exhibited a 3.5:1 mixture of two conformational isomers (UP and DOWN conformers).Keywords
This publication has 22 references indexed in Scilit:
- Total Synthesis of Ciguatoxin CTX3CScience, 2001
- Synthesis of Ciguatoxin (2S,5R)-ABC SegmentHETEROCYCLES, 2001
- Enantiocontrolled Synthesis of Trialkyl-Substituted Stereogenic Carbons. A General Route to cis-3,5-Dialkyl γ-LactonesOrganic Letters, 2000
- The Absolute Configuration of CiguatoxinJournal of the American Chemical Society, 1997
- Preparation of eight-membered cyclic ethers by Lewis acid promoted acetal-alkene cyclizationsJournal of the American Chemical Society, 1990
- Macromodel—an integrated software system for modeling organic and bioorganic molecules using molecular mechanicsJournal of Computational Chemistry, 1990
- Structures of ciguatoxin and its congenerJournal of the American Chemical Society, 1989
- Structure of brevetoxin A (GB-1 toxin), the most potent toxin in the Florida red tide organism Gymnodinium breve (Ptychodiscus brevis)Journal of the American Chemical Society, 1986
- Enantioselective synthesis and absolute configuration of (-)-.alpha.-kainic acidJournal of the American Chemical Society, 1982
- CYCLIZATION OF POLYENES XX, BROMO ETHERIFICATION OF UNSATURATED ALCOHOLS AND KETONESChemistry Letters, 1976