Synthesis of the BCDE rings of ciguatoxin 1B via an acetylene biscobalthexacarbonyl–vinylsilane strategy

A synthetic route to the BCDE rings of ciguatoxin 1B has been explored through acetylene biscobalthexacarbonyl complex and vinylsilane strategy. The key issues in the current synthesis are (i) ether ring cyclization by means of the acetylene cobalt complex and (ii) reductive decomplexation of the product endo-complexes into the corresponding vinylsilanes. A sequential cyclization route is also described along this line.