An Umpolung Approach to Acyclic 1,4‐Dicarbonyl Amides via Photoredox‐Generated Carbamoyl Radicals

• Published in: Chemistry : a European journal Vol. 29; no. 28; pp. e202300403 - n/a
• Main Authors: Williams, Jason D., Leach, Stuart G., Kerr, William J.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 16.05.2023; Wiley Subscription Services, Inc
• Subjects: Alkenes; Amides; Chemistry; Chemistry, Multidisciplinary; photochemistry; photoredox catalysis; Physical Sciences; radical reactions; Radicals; Science & Technology; synthetic methods; PHOTOCHEMICAL GENERATION; amides; ALKYL RADICALS; ACIDS; CATALYZED SYNTHESIS; ACYL RADICALS; radical reactions; REACTIVITY; photochemistry; CHEMISTRY; photoredox catalysis; synthetic methods; BETA-LACTAMS; CYCLIZATION
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202300403

A method for the generation and reaction of carbamoyl radicals from oxamate salts, followed by reaction with electron‐poor olefins, is described. The oxamate salt acts as a reductive quencher in the photoredox catalytic cycle, allowing mild and mass‐efficient formation of 1,4‐dicarbonyl products; a challenging transformation in the context of functionalized amide formation. Increased understanding has been obtained by the use of ab initio calculations, in support of experimental observations. Furthermore, steps have been taken towards an environmentally‐friendly protocol, by utilizing sodium as a cheap and low mass counterion, and demonstrating successful reactions using a metal‐free photocatalyst and a sustainable, non‐toxic solvent system. Photoredox catalysis is used to generate carbamoyl radicals from oxamate salts. Addition to a range of electron‐poor olefins gives the 1,4‐amido‐carbonyl products in good yields. The reaction proceeds under mild conditions, and a transition metal or organic photocatalyst can be employed.