Enantioconvergent radical addition of racemic alkyl halides to access vicinal stereocentres.

Abstract

The development of synthetic methods that convert readily accessible chemicals into highly valuable small organic molecules, especially those with enantioenriched three-dimensional structures, holds substantial importance in organic synthesis. Alkyl halides are pivotal substrates for generating chiral C(sp³)-C(sp³) bonds. However, constructing modular vicinal stereogenic carbon centres from racemic alkyl halides, especially those bearing the sterically bulky quaternary carbon stereocentres frequently found in natural products, remains a daunting challenge. Here we report cobalt-catalysed enantioconvergent reductive addition of racemic alkyl halides with imines, allowing for efficient construction of various contiguous stereogenic centres, including tertiary-tertiary, tertiary-quaternary and quaternary-quaternary stereocentres with high diastereo- and enantioselectivities. The mild reaction conditions circumvent the use of organometallic reagents, ensuring broad functional group compatibility and enabling the formation of valuable chiral organic motifs such as amino acids, organophosphorus compounds, amino alcohols and γ-lactams. This reductive radical addition protocol also enables the stereoselective construction of C-glycosyl amino acids.