Construction of Vicinal All-Carbon Stereogenic Centers via Copper-Catalyzed Asymmetric Decarboxylative Propargylation: Enantio- and Diastereoselective Synthesis of Substituted Spirolactones

Enantioselective Nickel-Catalyzed α-Spirocyclization of Lactones

Herein we report a strategy for the enantioselective synthesis of spirocycles containing all-carbon quaternary centers via nickel-catalyzed intramolecular addition of lactone enolates to aryl nitriles. The established lactone α-spirocyclization efficiently and enantioselectively forges 5-, 6-, and 7-membered rings, performing best in the synthesis of 7-membered rings (up to 90% ee). This discovery represents an expansion of the synthetic toolkit for enantioselective spirocyclization, providing access to chiral, pharmaceutically relevant spirocyclic products.

Electrochemical Synthesis of Spirolactones from α-Tetralone Derivatives with Methanol as a C1 Source

Spirolactones are widely found in pharmaceuticals and bioactive natural products. However, efficient and environmentally friendly approaches to accessing spirolactones are still highly desirable. Herein, a novel electrochemical synthesis of spirolactones from α-tetralone derivatives with methanol as a C1 source is described. This electrochemical reaction exhibits a high efficiency and good functional group tolerance.

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.

Copper-Catalyzed Enantioselective Formal [4 + 1] and [3 + 3] Cycloaddition of Ethynylethylene Carbonates

Herein we employed ethynylethylene carbonates (EECs) to achieve formal [4 + 1] and [3 + 3] cycloaddition with cyclic 1,3-dicarbonyl compounds. On one hand, EECs with styryl substitution could undergo a remotely controlled enantioselective [4 + 1] cycloaddition reaction. This reaction exhibits good chemoselectivity, regioselectivity, and enantioselectivity. In addition, a [3 + 3] cycloaddition reaction of EECs with cyclic 1,3-dicarbonyl compounds was also achieved, leading to a series of 4H-pyrans with impressive chemoselectivity and enantioselectivity.

Organocatalytic Enantioselective Intramolecular Michael Addition by In Situ Generated Aminoisobenzofulvenes: Construction of Spiro Quaternary Carbon Stereocenters

An unprecedented enantioselective organocatalytic spirocyclization strategy is presented by in situ generation of aminoisobezofulvenes. The reaction sequence involves a reductive Michael/aldol-condensation/Michael addition cascade by iminium-enamine catalysis. The key success of this spirocyclization was the formation of intermediatory nucleophilic aminoisobenzofuvenes accountable for intramolecular Michael addition. Benzospirononanes featuring an all carbon qauternary spirocenter were obtained using proline-derived amino-organocatalyst in moderate to good yields and excellent diastereo- and enantioselectivities (up to >20 : 1 dr, and 99 % ee). Post-methodological manipulation of benzospirononanes was also demonstrated.