Isoxazole --> benzisoxazole rearrangement promoted cascade reactions affording stereodefined polycycles.

[reaction: see text] A new chemo-, regio-, and stereoselective cascade reaction features a novel isoxazole --> benzisoxazole rearrangement and affords highly functionalized, differentially protected compounds. The products of this reaction are directly converted to a number of complex, structurally diverse polycyclic molecules. These transformations highlight the unique chemistry inherent to readily prepared fused isoxazoles.