Fig. 1: Asymmetric [3 + 2] annulation of propargylic esters to chiral dihydrofuran derivatives with cyclic quaternary stereocenters.

a Selected examples of important molecules with cyclic chiral quaternary carbon center. b Cu-catalyzed propargylation/cycloisomerization reactions. c Proposed binuclear Cu-allenylidene intermediates. d This work: dinuclear copper-catalyzed [3 + 2] annulation of tertiary propargylic esters with a diverse set of C,O bis-nucleophiles.