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.

Rh-Catalyzed Twofold Conjugate Addition of 2-Arylimidazo[1,2-a]pyridines to p-Quinols To Access Bridged Scaffolds with Three Contiguous Stereocenters.

A Rh(III)-catalyzed annulation of 2-arylimidazo[1,2-a]pyridines with p-quinols has been realized, leading to bridged heterocycles with three contiguous stereocenters via a twofold conjugate addition. The cascade reaction is diastereoselective and proceeds through a sequential Rh-catalyzed ortho C(sp2)-H functionalization of the aryl group of imidazo[1,2-a]pyridine with p-quinol followed by an intramolecular conjugate addition to provide a series of diverse, novel bridged heterocycles.