Access to All‐Carbon Spirocycles through a Carbene and Thiourea Cocatalytic Desymmetrization Cascade Reaction

Harmony between cats: Dual carbene and thiourea catalysis enabled rapid asymmetric access to spirocyclic compounds by a desymmetrization process (see scheme). The presence of the thiourea cocatalyst was essential for this carbene‐catalyzed enantioselective synthesis of all‐carbon spirocycles to proceed. The reaction products can be readily transformed into sophisticated multicyclic molecules and chiral ligands.

Abstract

A new catalytic approach for rapid asymmetric access to spirocycles is disclosed. The reaction involves a carbene‐ and thiourea‐cocatalyzed desymmetrization process with the simultaneous installation of a spirocyclic core. The use of a thiourea cocatalyst is critical to turn on this reaction, as no product was formed in the absence of a thiourea. Our study constitutes the first success in the carbene‐catalyzed enantioselective synthesis of all‐carbon spirocycles. The reaction products can be readily transformed into sophisticated multicyclic molecules and chiral ligands.

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