Syntheisis of the ABCD ring system of azaspiracid,a marine poison from Mytilus Edulis

摘要

Synthesis of the ABCD ring system of azaspiracid (1) was accomplished.The bridge system between the B and C ring using a sulfur atom,supported the spiroacetal-construction at the C13 position in the natural form.The stereochemistry was confirmed by the NOE experiments,along with conversion under acidic conditions into the unnatural derivative (12).