Dynamic multiligand catalysis: A polar to radical crossover strategy expands alkyne carboboration to unactivated secondary alkyl halides

We describe a dual strategy in Cu catalysis based on an unprecedented dynamic multiligand coordination pool that triggers cooperative polar/radical pathways in a single catalytic cycle. This strategy has been applied to address a restricting limitation inherent to Cu-catalyzed B(2)pin(2)-carboboration of alkynes-the very low reactivity of the intermediate vinyl-Cu(I) species, which renders conventional methods ineffective with alkyl electrophiles other than simple primary halides. The crossover strategy enabled by ligand exchange in an organometallic intermediate overcomes this reactivity issue, expanding the scope of carboboration to unactivated secondary alkyl halides, and opens new avenues to access stereodefined tetrasubstituted vinylboronates. The method is regio- and stereoselective, shows excellent functional group tolerance, and allows the incorporation of complex carbo- and heterocyclic fragments at either reaction partner.

Automated summary

A novel dual Cu catalysis strategy based on a dynamic multiligand coordination pool is described, triggering cooperative polar/radical pathways in a single catalytic cycle. This strategy overcomes the reactivity issue in Cu-catalyzed carboboration, expanding the scope of the reaction and opening avenues to access stereodefined tetrasubstituted vinylboronates.