Selenium Dioxide Promoted α ‐Keto N ‐Acylation of Sulfoximines Under Mild Reaction Conditions

NaI-mediated α-keto-acylation of NH-sulfoximines with aryl methyl ketones

A room-temperature NaI-mediated oxidative sulfoximidation of aryl methyl ketones to synthesize α-keto-N-acyl sulfoximines has been disclosed. This metal- and base-free NH-sulfoximidation is facilitated by tert-butyl hydroperoxide (TBHP) as the oxidant, affording α-ketoamides with good functional group tolerance, broad substrate scope, and scalability. Mechanistic investigations indicate the intermediacy of radicals and highlight molecular oxygen's significance as the oxygen source.

NIS-initiated photo-induced oxidative decarboxylative sulfoximidation of cinnamic acids

N-Iodosuccinimide catalyzed, visible-light-induced oxidative decarboxylative cross-coupling between cinnamic acids and NH-sulfoximines is presented. This strategy results in the formation of α-keto-N-acyl sulfoximines via the construction of two new CO bonds and one C-N bond. The in situ-generated N-iodosulfoximine serves as the light-absorbing species in the absence of any external photosensitizer. The keto carbonyl and amidic carbonyl oxygen in the resulting product originate from dioxygen and water respectively.

Silver-mediated Room Temperature Reactions for the Synthesis of N-α-Ketoacyl Sulfoximines and N-α,β-Unsaturated Acyl Sulfoximines

Here, we report a silver-mediated coupling of acetylenes with sulfoximines to synthesize N-α-ketoacyl sulfoximines and N-α,β-unsaturated acyl sulfoximines. The reactions are performed under an open atmosphere using the oxidant K₂S₂O₈ and the ligand 2,2-bipyridyl. However, the fate of the product formation is controlled by the type of substrate used. The coupling between aryl acetylenes and sulfoximines afforded the N-α-ketoacylsulfoximines, while the alkyl acetylenes provided the N-α,β-unsaturated acyl sulfoximines. Controlled experiments reveal the differential reactivity patterns of substrates. The labeling ¹⁸O experiments showed that water is the source of the incoming oxygen atom for the keto group of N-α-ketoacyl sulfoximines and N-α,β-unsaturated acyl sulfoximines.

Visible-Light-Induced N-Acylation of Sulfoximines

A metal-, base-, and additive-free N-acylation of sulfoximines was developed under mild conditions using organic photoredox catalyst. This green strategy featured broad substrate scope, good compatibility with air, and high yields (up to 96%). It could be further applied to amino acid modifications and α-keto N-acyl sulfoximine synthesis without any complicated transformations or operations.

Visible-Light-Mediated α-Ketoacylations of NH-Sulfoximines with gem-Difluoroalkenes

A photochemical approach for the preparation of α-keto-N-acyl sulfoximines from NH sulfoximines and gem-difluoroalkenes has been developed. In the presence of NBS, the reactions proceed in air without the need of a photocatalyst or additional oxidant. Results of mechanistic studies suggest that the two oxygens in the products stem from water and dioxygen.