Controlled Relay Process to Access N-Centered Radicals for Catalyst-free Amidation of Aldehydes under Visible Light

N-Chloro-N-sodio-carbamates as a Practical Amidating Reagent for Scalable and Sustainable Amidation of Aldehydes under Visible Light

“…17 This is also an important objective in the fields of amide synthesis, as the most widely employed solvents in both small and large scale amidation reactions are still those with major regulatory issues (e.g., CH 2 Cl 2 or DMF). 18 In the previous report, 7 we utilized α,α,α-trifluorotoluene (PhCF 3 ) solvent for most of the substrate scopes owing to the superior efficiency. In search of a greener alternative, we carried out further solvent screenings in a model reaction of benzaldehyde with N-chloro-N-sodio salt 3 (Table 1).…”

“…In this context, we recently reported a new synthetic approach that harnesses N-chloro-N-sodio-carbamates II and visible light to transform aldehydes I to N-alkoxycarbonyl amides III under mild and convenient conditions (Figure 1a). 7 This strategy relies on a relay process that slowly incorporates photoactive N-chloroamide radical precursor V by the reaction between the amidating reagent II and in situ generated acid chloride intermediate IV, which subsequently allows controlled access to the N-centered radical 8 VI via N−Cl homolysis under visible light (Figure 1b). Hydrogen atom transfer (HAT) 9 of an aldehydic C−H (I) to the nitrogen center then leads to the amide product III, while the translocation of N to the C radical (VII) is followed by chlorine abstraction or coupling with the Cl radical to further generate acid chloride IV to iterate the relay cycle.…”

Three-component 1,2-carboamination of vinyl boronic estersviaamidyl radical induced 1,2-migration

“…The proposed mechanism is shown in Scheme 4b . As chloroamides have been recently proposed to undergo homolysis under visible light irradiation, 19 a,b we propose that initiation proceeds via homolytic N–Cl cleavage generating the electrophilic amidyl radical A, which then adds to the electron-rich vinylboron ate complex 2a to give the adduct boronate radical B. The radical anion B then undergoes single electron transfer (SET) oxidation with 3a in an electron-catalyzed process 20 a,b or chloride atom transfer with 3a to provide C or D along with the amidyl radical A, thereby sustaining the radical chain.…”

Visible‐Light Induced C(sp2)−H Amidation with an Aryl–Alkyl σ‐Bond Relocation via Redox‐Neutral Radical–Polar Crossover

“…[4d, 5c, 9] Recent advances in photoredox catalysis have witnessed the resurgence of radical chemistry to become an extremely useful synthetic tool. [10] While the reactivity of photogenerated N-centered radicals [11] toward s- [12] and p-bonds [13] has been widely investigated, their ipso-reactivity is relatively less explored. In fact, Wang [14] and Cho [15] independently highlighted net-oxidative spirocyclization reactions by using amidyl and iminyl radicals, respectively.…”