Gold-Catalyzed [3+2] Annulation, Carbenoid Transfer, and C-H Insertion Cascade: Elucidation of Annulation Mechanisms via Benzopyrylium Intermediates

It has been established that a cationic gold(I)/PCy3 complex catalyzes the intramolecular cascade reaction of enediyne-carbonyls via benzopyrylium intermediates giving pentacyclic compounds, bearing five or six stereocenters with high yields and diastereoselectivity. In this cascade reaction, [3 + 2] annulation, carbenoid transfer, and C-H insertion proceed in one-pot. The DFT calculation revealed that both the [3 + 2] and [4 + 2] annulations proceed via the same gold(I) carbenoid, produced by the [3 + 2] cycloaddition, and the reaction between the gold(I) carbenoid and the additional alkyne unit promotes the present cascade reaction.

Automated summary

The study showed that a cationic gold(I)/PCy3 complex catalyzes the intramolecular cascade reaction of enediyne-carbonyls, yielding pentacyclic compounds. The cascade reaction involves [3 + 2] annulation, carbenoid transfer, and C-H insertion in one-pot.