Design of 1-Phosphanorbornene Derivatives as Chiral Organocatalysts for Enantioselective (4+2) Annulation Reactions of γ-Benzyl Allenoates

Two novel diastereoisomeric P-chirogenic phosphine catalysts, i.e., JiaPhos, which can be easily derived from inexpensive and commercially available starting materials in five chemical operations (totally 4.16g scale), are introduced. To our delight, the JiaPhos catalysts display good performance in enantioselective (4 + 2) annulations involving 3-methylene-2-oxindoles and gamma-benzyl allenoates, providing a wide range of 3,3'-spirocyclic oxindoles with good efficiency and enantioselectivity.

Automated summary

Two novel diastereoisomeric P-chirogenic phosphine catalysts, JiaPhos, were successfully synthesized from inexpensive starting materials in five chemical operations on a 4.16g scale. These catalysts demonstrated excellent performance in enantioselective (4 + 2) annulations, providing a diverse range of 3,3'-spirocyclic oxindoles with high efficiency and enantioselectivity.