Direct Assembly of Chiral Alkyl Radical Precursors via Enantioselective NHC-Catalyzed Redox-Esterification of N-Hydroxyphthalimide (NHPI)

Enantioselective redox esterification catalyzed by N-heterocyclic carbenes (NHCs) provides efficient access to N-hydroxyphthalimide (NHPI) esters from readily available β-substituted enals. This atom-economic transformation installs β-stereocenters with high enantioselectivity, furnishing saturated NHPI esters that serve as versatile precursors to chiral alkyl radicals. Owing to the broad synthetic utility of NHPI esters in photoredox and electrochemical decarboxylations, this strategy establishes a new asymmetric entry point for radical chemistry. The method’s practicality is demonstrated by one-pot downstream Giese additions. A pronounced positive non-linear effect indicates dual NHC involvement in the enantio-determining β-protonation of the catalytic NHC-homoenolate intermediate