Chiral Phosphine Ligands of COAP and SKP Switched Regiodivergent Asymmetric Allylic Alkylation of MBH Adducts

The palladium-catalyzed highly regioselective asymmetric allylic alkylation of 3'-indolyl-3-oxindole derivatives with Morita-Baylis-Hillman (MBH) carbonates was developed to facilely construct chiral 3,3'-bisindole derivatives under mild reaction conditions. The regioselectivity (α/γ) of MBH carbonates was efficiently switched in the presence of chiral oxalamide phosphine or spiroketal-based diphosphine/Pd(0) complexes as a chiral catalyst. A series of multifunctional 3,3'-bisindole derivatives with all-carbon quaternary stereogenic centers were obtained in high yields with good to excellent enantio-, diastereo-, and regioselectivity. The present process is endowed with some salient features such as broad substrate scope, N-protecting group-free, excellent stereoselectivity, as well as adjustable regioselectivity.

Substrate-directed divergent annulations of sulfur ylides: synthesis of functionalized bispirocyclopentane and bispirocyclopropane derivatives

Herein, an efficient, substrate-directed divergent [2 + 3]/[2 + 1] annulation of tetra-substituted oxa-dienes and allylic sulfur ylides has been successfully developed. Under precise annulation regulation, a series of functionalized bispirocyclopentane and bispirocyclopropane derivatives were synthesized in a highly stereoselective and economical manner (up to 95% yield, >20 : 1 dr or >20 : 1 E/Z). This protocol offers the advantages of mild conditions, high chemo-, regio- and diastereoselectivity and broad substrate compatibility. In addition, the synthetic practicality of this protocol was evaluated through a scale-up preparation and a series of three-component reactions utilizing in situ generated sulfur ylides.

Atroposelective Access to Dihydropyridinones with C-N Axial and Point Chirality via NHC-Catalyzed [3 + 3] Annulation

An N-heterocyclic carbene-catalyzed atroposelective [3 + 3] annulation of enals with 2-aminomaleate derivatives is described. A series of substituted dihydropyridones bearing both C-N axis and point chirality were synthesized with good diastereo- and enantioselectivity under mild conditions. This efficient strategy successfully superpositions an extra point chiral element with an axial backbone, and the generated structurally interesting atropisomers may have potential application in drug discovery.

Synthesis of Trifluoromethylated γ-Lactams through Radical Cascades of N-Cyano Alkenes with CF3SO2Na

We report herein a facile strategy to synthesize trifluoromethylated γ-lactams through trifluoromethylcarbonylation of N-cyano alkenes using readily available CF₃SO₂Na as the CF₃ radical source. A range of trifluoromethyl-containing γ-lactams was obtained in good yields. This transition-metal-free protocol is demonstrated with mild conditions, broad substrate scope, good functional group tolerance, convenient reagents, and an easy-to-handle operating system.

N-Heterocyclic Carbene-Catalyzed [3 + 2] Annulation of 3,3'-Bisoxindoles with α-Bromoenals: Enantioselective Construction of Contiguous Quaternary Stereocenters

An NHC-catalyzed enantio- and diastereoselective [3 + 2] annulation of α-bromoenals with bisoxindoles is developed, affording efficient access to various spirocyclic bisoxindole alkaloids. This protocol tolerates a broad substrates scope, with various spirocyclic bisoxindoles obtained in generally excellent enantioselectivities. More importantly, two contiguous sterically congested all-carbon quaternary stereocenters are successfully created during this process.