Synthesis of the BCD-ring of ciguatoxin 1B using an acetylene cobalt complex and vinylsilane strategy

Synthesis of the tricyclic BCD-ring segment with high stereoselectivity has been achieved starting from a sugar derivative directed toward the synthesis of the left part of ciguatoxin 1B. The central reactions in the synthesis are (i) ether ring formation mediated by an acetylene cobalt complex, (ii) decomplexation of the endo-acetylene cobalt complex to the vinylsilane, and (iii) ring-opening reaction of the epoxysilane into the allylic alcohol.