Photochemical Regioselective C(sp³)–H Amination of Amides Using N-Haloimides

Abstract

A metal-free regioselective C­(sp3)–H amination of amides using N-haloimides in the presence of lithium tert-butoxide and visible light is presented herein. This photoexcited approach is straightforward, and it aminates a wide variety of amides under mild conditions without the use of photocatalysts, external radical initiators, or oxidants. A halogen-bonded intermediate between the tert-butoxide base and the N-haloimide is proposed to be responsible for the increased photoreactivity. Calculations show that the formation of this electron donor–acceptor complex presents an exergonic energy profile.

Dimsyl Anion Enables Visible‐Light‐Promoted Charge Transfer in Cross‐Coupling Reactions of Aryl Halides

“…This transition has a charge-transfer excitation character originating from the dimsyl anion molecular orbital (MO) π HOMO to the aryl halide MOs σ LUMO , π LUMO + 1 and π LUMO + 2 with a 14%, 73%, and 8% contribution, respectively (supporting information S29-34). Based on previous reports of KOtBu performing SET, [11,16] we performed various DFT calculations with analogous complexes involving À OtBu and aryl iodide (see supporting information S31-S34). Unfortunately neither halogen-bonded intermediates nor anion-π complexes modeled in our study had charge-transfer character, further eroding a potential involvement of À OtBu in the SET step.…”

“…Our interest in photoinduced SET performed by KOtBu, recently led us to identify a halogen-bonded EDA complex capable of CÀ H aminations. [16] Herein, an unprecedented EDA complex between dimsyl anion and aryl halides is reported that is responsible for a photo-induced activation of aryl halides and enables a visible-light-promoted CÀ S, CÀ Se, and CÀ Te crosscoupling with diaryl dichalcogenides (Scheme 1C). The reaction proceeds at room temperature in the absence of catalysts generating the desired products in good to excellent yields across a range of substrates.…”

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

“…The above reactions involve radical intermediates I 9 and/or I 4 . Borylation [130][131][132], silylation [133], and amidation [134] of N-adjacent C-H bond of DMAc have been achieved with bis(pinacolato)diboron and Rh or Ir catalysis (Scheme 41a,b), triethylsilyl hydride, Ru catalysis, and tert-butylethylene as the hydrogen acceptor (Scheme 41c), and N-haloimides under blue light irradiation (Scheme 41d). The transition-metal catalysis could involve the C(sp 3 )−H bond oxidative addition to the metal center [135,136] while the photochemical conditions promote the formation of radical I 9 [134].…”

Transition-Metal-Free Photoredox Phosphonation of Aryl C–N and C–X Bonds in Aqueous Solvent Mixtures

“…Our interest in the development of metal-free green synthetic methodologies, − recently led us to explore new approaches for the radical activation of aryl halides . Here, we report the first metal-free photoredox-catalyzed phosphonation of aryl trimethylammonium salts and aryl halides (iodides and bromides) using affordable phosphite reagents in green aqueous solvent mixtures.…”