Synthetic Studies Toward the Spiroimine Unit of the Spirolides

Synthetic studies toward the spiroimine unit of the spirolide family of shellfish biotoxins are described. Several strategies for introduction of the C7, C29, and C32 stereo- centers of the A,E-ring system of the spirolides are described, such as spironitrone formation, Birch reductive alkylation, and asymmetric Diels-Alder cycloadditions.