Copper-Catalyzed Diastereo- and Enantioselective Decarboxylative [3 + 2] Cyclization of Alkyne-Substituted Cyclic Carbamates with Azlactones: Access to γ-Butyrolactams Bearing Two Vicinal Tetrasubstituted Carbon Stereocenters

Squaramide-catalyzed aza-Michael/Michael cyclization cascade reaction: one-pot enantioselective construction of highly functionalized γ-lactams

We report a squaramide-catalyzed aza-Michael/Michael cyclization of nitroalkenes with 3-benzoylacylamides, facilitating the asymmetric synthesis of γ-lactams. This method efficiently generates a range of optically pure γ-lactams, in yields ranging from 25% to 90% and enantioselectivities 71% to 99% under mild conditions. Moreover, this reaction demonstrates exceptional compatibility with a variety of functional groups and offers a wide array of subsequent transformation possibilities.

Palladium-Catalyzed Decarboxylative Allylic Sulfonylation of Vinyloxazolidine-2,4-diones: Synthesis of γ-Sulfonyl-α,β-unsaturated Amides

A palladium-catalyzed decarboxylative allylic sulfonylation reaction of vinyloxazolidine-2,4-diones with inexpensive and readily available sodium sulfinates as sulfonylation reagents has been developed. Under the catalysis of Pd(PPh3)4, a wide range of γ-sulfonyl-α,β-unsaturated amides can be synthesized in good to excellent yields. The developed protocol is characterized by exclusive regioselectivity, mild reaction conditions, broad substrate scope, good functional group tolerance, and suitable for gram-scale synthesis.

Electrochemical Reductive Bimolecular Cycloaddition of 2-Arylideneindane-1,3-diones for the Synthesis of Spirocyclopentanole Indane-1,3-diones

An electrochemical reductive bimolecular cycloaddition of 2-arylideneindane-1,3-diones has been reported for the synthesis of spirocyclopentanole indane-1,3-diones bearing five contiguous stereocenters with vicinal tetrasubstituted stereocenters, especially involving a quaternary carbon center, in moderate to good yields and excellent diastereoselectivities. The present protocol features mild reaction conditions, no external chemical redox reagents, excellent atom economy, and gram-scale synthesis. In addition, a mechanistic investigation indicates that the reactions proceed through a radical pathway.

Palladium-Catalyzed Asymmetric Decarboxylation of 5-Vinyloxazolidine-2,4-Diones Triggering the Dearomatization of Electron-Deficient Indoles for the Synthesis of Chiral Highly Functionalized Pyrroloindolines

A catalyst system consisting of a chiral phosphoramidite ligand and Pd2(dba)3·CHCl3 causes the decarboxylation of 5-vinyloxazolidine-2,4-diones to generate amide-containing aza-π-allylpalladium 1,3-dipole intermediates, which are capable of triggering the dearomatization of 3-nitroindoles for diastereo- and enantioselective [3+2] cycloaddition, leading to the formation of a series of highly functionalized pyrroloindolines containing three contiguous stereogenic centers with excellent results (up to 99% yield, 88:12 dr, and 96% ee).

Regioselectivity Switch of α-Amino Acid-Derived Esters and MBH Carbonates for the Synthesis of Allyl-Substituted Azlactones

Allylic azlactones are greatly significant in terms of potential bioactivities and synthetic applications. Owing to the burgeoning interest of the pharmaceutical industry in α-amino acid derivatives, discovering strategies for the synthesis of allylic azlactones is important. Herein, we establish a transition-metal-free regioselectivity switch of α-amino acid-derived esters and MBH carbonates, which exhibits broad reaction scope and good reaction yields. Control reactions indicate that both base and solvent are important for regioselectivity.

Decarboxylative [3 + 2] cycloaddition of propargyl cyclic carbonates with C,O-bis(nucleophile)s to access dihydrofuro[3,2-c]coumarins and dihydronaphtho[1,2-b]furans with quaternary center

The development of efficient and straightforward strategies for obtaining chiral complex molecules from readily available starting materials is of great value in drug discovery. The stereodivergent synthesis of heterocycles bearing quaternary centers remains a challenge due to inherent steric issues. Herein, we report an enantioselective copper-catalyzed decarboxylative [3 + 2] cycloaddition of propargyl cyclic carbonates/carbamates with 4-hydroxycoumarins to afford a wide range of dihydrofuro[3,2-c]coumarins in excellent yields and enantioselectivity. The strategy has been successfully applied to other C,O-bisnucleophiles, such as α-naphthols, to obtain dihydronaphtho[1,2-b]furans with good yields.