Enantioselective construction of cyclic quaternary stereocenters via dinuclear copper catalyzed asymmetric [3 + 2] propargylation/annulation.

Abstract

While copper-catalyzed asymmetric propargylic substitution has emerged as a versatile tool for constructing chiral propargylic frameworks, its application in forging cyclic chiral quaternary carbon centers remains a significant synthetic challenge. This work demonstrates a dinuclear copper-catalyzed asymmetric [3 + 2] annulation strategy between tertiary propargyl carbonates and diverse C,O-bisnucleophiles under mild conditions. The protocol enables efficient synthesis of chiral dihydrofurans featuring cyclic quaternary stereocenters with broad substrate compatibility. The stereochemical control may arise from the unique coordination geometry of dinuclear copper-allenylidene intermediates, which spatially aligns the electrophilic site within the chiral ligand environment. This spatial arrangement overcomes inherent steric challenges in the stereoselective formation of quaternary carbons bearing dual alkyl substituents, offering mechanistic insights into cooperative dinuclear catalysis for asymmetric transformations.