Enantioselective Ni-Al Bimetal-Catalyzed Cycloaddition of Cyclopropyl Ketones with Alkynes under Mild Conditions.

Transition metal-catalyzed enantioselective intermolecular cycloaddition of cyclopropyl ketones and π-unsaturated compounds represents a long-standing challenge in the asymmetric C-C bond activation of cyclopropanes. Developed strategies rely on substrate modifications to mitigate racemization or to stabilize radical intermediates. In contrast, an efficient approach governed by transition-metal catalysts for general cyclopropyl ketones remains an elusive challenge. Herein, we report a highly active chiral diamine-phosphine oxide-ligated Ni-Al bimetallic catalyst that promotes enantioselective C-C cycloaddition under mild conditions. This system effectively suppresses product racemization and affords a diverse range of cyclopentyl ketones bearing a chiral α-tertiary carbon center in up to 99% yield and 99% ee.