Photoinduced, Copper-Catalyzed Enantioconvergent Azidation of Alkyl Halides

Although the nucleophilic substitution of alkyl halides by azide is perhaps the most widely used method for the synthesis of organic azides, we are aware of only two reports of enantioselective variants of this classic transformation. In this study, we establish that a photoinduced chiral copper catalyst (generated in situ from commercially available components) can achieve enantioconvergent azidations of racemic secondary and tertiary alkyl halides (α-halocarbonyl compounds). The resulting enantioenriched alkyl azides are useful end points and building blocks in synthesis. Mechanistic studies furnish support for key intermediates in the proposed catalytic cycle, including copper-azide complexes and an organic radical.