Unified synthesis of the DEF and GhI ring systems of maitotoxin

Unified synthesis of 6/6/6-tricyclic ethers corresponding to the DEF and GHI ring systems of maitotoxin was achieved from a common intermediate prepared from a furan derivative and a terminal olefin via FujiwaraMoritani reaction, followed by Sharpless asymmetric dihydroxylation, and Achmatowicz reaction. The DEF ring was synthesized from the common intermediate via regio- and stereoselective borylation of an enone, and methylation of an S, O-acetal. On the other hand, the GHI ring was synthesized from the common intermediate via reductive etherification, Sharpless asymmetric dihydroxylation, and BartonMcCombie deoxygenation.