Sulfone as a Transient Activating Group in the Palladium-Catalyzed Asymmetric [4 + 3] Cycloaddition of Trimethylenemethane Enabling the Enantioselective Synthesis of Fused Azepines

High-order dipolar annulations with metal-containing reactive dipoles

“…On the other hand, o -quinomethides ( o -QMs) and styryl-substituted o -QMs 15 were also employed as substrates with Trost's reaction conditions, and they delivered a series of benzo[ b ]oxepines bearing nitro-, CN, SO 2 Ph and quaternary carbon with high efficiency and enantioselectivity. Shortly after, similar transformations were further developed by the Shao group 28 and Deng group, 29,30 which demonstrate the generality of the Pd-catalyzed (3+4) annulation strategy for construction of 7-membered heterocycles.…”

Palladium-catalyzed [4 + 2] cycloaddition of amido-tethered allylic carbonates with oxazol-5-(4H)-ones: synthesis of piperidine-2,6-dione derivatives

“…1–3 In particular, an array of self-deprotonated or sequentially decarboxylated/deprotonated TMM precursors such as nitrile, trifluoromethyl, aldehyde, benzophenone imine, aza-aryl, and phospha-TMM have been utilized in [3 + n] cycloaddition reactions (Scheme 1a). 4–7 These types of Pd-TMM 1,3-carbodipoles generally produced five-membered rings with few exceptions. In further exploration, Pd-stabilized all carbon-1,4-dipoles were developed by using an additional carbon atom and were used to achieve [4 + n] cycloaddition reactions, forming a variety of cyclic structures (Scheme 1a).…”

Advances in Vinyl Sulfone Catalyzed Synthesis: Methods, Mechanisms and Perspectives

“…[3][4][5][6] Therefore, vinyl sulfones are often used as chemical chameleons. [7][8][9] Sulfone bases have unique chemical properties owing to the easy oxidation of the S=O bond, and the CÀ S bond connected to sulfur can be easily reduced and cleaved to generate carboanions and carbon center radicals. As a strong electron-absorbing group, sulfone can activate the deprotonation of adjacent protons and conjugated π bond addition, but can also act as a nucleophile.…”