Copper-Catalyzed Asymmetric\nNucleophilic Opening of\n1,1,2,2-Tetrasubstituted Donor–Acceptor Cyclopropanes for the\nSynthesis of α‑Tertiary Amines

Catalytic asymmetric transformation of donor–acceptor\ncyclopropanes\n(DACs) has been proven to be a highly valuable and robust strategy\nto construct diverse types of enantioenriched molecules. However,\nthe use of 1,1,2,2-tetrasubstituted DACs to form products bearing\nquaternary stereocenters remains a long-term unsolved challenge. Here,\nwe report the copper-catalyzed asymmetric aminative ring opening of\ntetrasubstituted alkynyl DACs that delivers a myriad of α-tertiary\namines with high levels of enantioselectivities. The alkyne, amine,\nand ester moieties within the products enable diverse further applications,\nincluding the asymmetric synthesis of bioactive molecules. Mechanistic\nstudies indicate that the zwitterionic intermediate bearing a copper-acetylide\nunit plays a key role in the process, which represents a new mode\nfor achieving catalytic asymmetric transformation of DACs.