November 2024

Allylic ethers are a common occurrence in natural products, and are often used as intermediates in target-oriented synthesis. Their synthesis often relies on the use of transition-metal catalysts. Here, we report an organocatalytic method for the allylation of O-centered nucleophiles, the Lewis base catalyzed allylation of silyl ethers with allylic fluorides. The method relies on the concept of latent pronucleophiles in Lewis base catalysis to overcome common limitations in substrate scope, even permitting the allylation of sterically congested O-pronucleophiles. When chiral Lewis base catalysts are used, the allyl ethers are produced in an enantioenriched form through kinetic resolution of fluorides, where the stereoselectivity is determined by the chiral catalyst.

Spirocyclobutanes have gained significant attention in medicinal chemistry discovery programs due to their broad spectrum of biological activities and clinical applications. Utilizing ring strain in small molecules to drive organic transformations is one of the most powerful tools in chemical synthesis. Our research group has focused on developing new synthetic strategies enabled by ring strain to construct complex molecules selectively and efficiently. This account summarizes our recent efforts toward the synthesis of a library of functionalized spirocyclobutanes by harnessing the ring strain of bicyclo[1.1.0]butanes. Three spicrocyclization cascades have been developed to incorporate a diverse range of radical precursors into spirocycobutanes.1 Introduction2 Synthesis of Spirocyclobutyl Lactones and -Lactams using Bifunctional Reagents3 Dual Photoredox/Nickel Catalysis for the Synthesis of Spirocyclobutyl Lactams4 Synthesis of Spirocyclobutyl Oxindoles under Photoredox Catalysis5 DFT Studies6 Conclusion