Kirmse–Doyle‐ and Stevens‐Type Rearrangements of Glutarate‐Derived Oxonium Ylides

A novel chemoenzymatic synthetic cascade enables the preparation of densely decorated tetrahydrofuran building blocks. Here, the lipase‐catalyzed desymmetrization of 3‐alkoxyglutarates renders highly enantioenriched carboxylic acid intermediates, whose subsequent activation and oxonium ylide rearrangement by means of rhodium or copper complexes furnishes functionalized O‐heterocycles with excellent diastereoselectivity. The two‐step protocol offers a streamlined and flexible synthesis of tetrahydrofuranones bearing different benzylic, allylic or allenylic side chains with full control over multiple stereogenic centers.