Total Synthesis of Asimicin via Highly Stereoselective [3 + 2] Annulation Reactions of Substituted Allylsilanes

A highly stereoselective total synthesis of (+)-asimicin (1) is reported. The synthesis features two chelate-controlled [3 + 2] annulation reactions-one of which (e.g., 2 + 3) constitutes a key, convergent fragment assembly step-that establish all of the stereochemistry of the bis-tetrahydrofuran unit of the natural product.