Visible Light-Promoted Radical Relay Cyclization/C–C Bond Formation of N-Allylbromodifluoroacetamides with Quinoxalin-2(1H)-ones

Abstract

A visible light-promoted radical relay of N-allylbromodifluoroacetamide with quinoxalin-2­(1H)-ones was developed in which 5-exo-trig cyclization and C–C bond formation were involved. This protocol was performed under mild conditions to facilely offer a variety of hybrid molecules bearing both quinoxalin-2­(1H)-one and 3,3-difluoro-γ-lactam motifs. These prepared novel skeletons would expand the accessible chemical space for structurally complex heterocycles with potential biological activities.

Visible‐Light‐Driven Cyclizations

“…[95] A similar reaction was developed by Chen and Yang in 2021, where N-allylbromodifluoroacetamides 323 react with quinoxaline-2(1H)-ones 327 under visible light using fac-Ir(ppy) 3 VII as catalyst. [96] The mechanism is totally analogous to the previous one, using quinoxaline-2(1H)-ones 327 as the initial radical this time, activated by the excited photocatalyst. The final difluoropyrrolidones 328 were obtained with moderate to good yields (38-80%) and good functional group tolerance (Scheme 62).…”

Photoinduced Three-Component Difluoroamidosulfonylation/Bicyclization: A Route to Dihydrobenzofuran Derivatives

“…In light of these above-mentioned experimental results and literature reports, ,, a plausible mechanism for this photoinduced radical cascade bicyclization is proposed (Scheme ). Initially, a charge-transfer complex A is formed by the combination of 2a and DABCO·(SO 2 ) 2 .…”

“…In particular, the introduction of a CF 2 group into γ-lactams with interesting biological profiles has been intensively studied. N -Allylbromodifluoroacetamides have been widely utilized as precursors to generate3,3-difluoro-γ-lactams derivatives, most of which adopt two-component strategies with transition-metal catalysts or photocatalysts . Nevertheless, the use of N -allylbromodifluoroacetamides as multicomponent synthons with alkynes specifically without any catalysts remains challenging and has hardly been explored.…”

Regioselective C-3-alkylation of quinoxalin-2(1H)-ones via C–N bond cleavage of amine derived Katritzky salts enabled by continuous-flow photoredox catalysis

“…9 More recently, Xuan et al explored a method for alkylation of quinoxalin-2(1 H )-ones that utilizes 4-alkyl-1,4- dihydropyridines (R-DHPs) as alkyl radical precursors via visible light photoredox catalysis. 10 Several research groups, including Zhang, 11 Yu, 12 Zhao, 13 Li, 14 Wang 15 and Yang 16 were developed different strategies for functionalizing quinoxalin-2(1 H )-ones, which are well documented in the current literature.…”