Halogen-Bond-Promoted Double Radical Isocyanide Insertion under Visible-Light Irradiation: Synthesis of 2-Fluoroalkylated Quinoxalines

Abstract

A halogen-bond-promoted double radical isocyanide insertion with perfluoroalkyl iodides is reported. With perfluoroalkyl iodides as halogen-bond donors and organic bases as halogen-bond acceptors, fluoroalkyl radicals can be generated by a visible-light-induced single electron transfer (SET) process. The fluoroalkyl radicals are trapped by o-diisocyanoarenes to give quinoxaline derivatives. This mechanistically novel strategy allows the construction of 2-fluoroalkylated 3-iodoquinoxalines in high yields under visible-light irradiation at room temperature.

Transition metal- and organophotocatalyst-free perfluoroalkylation reaction of amino(hetero)aromatics initiated by the complex [(TMEDA)I·I3] and visible light

“…A complex between a nitrogen base and R F -I has very recently been postulated to generate R F radicals upon visible light irradiation. [18][19][20] We have also observed the same trends for the formation of a complex TMEDA$2C 4 F 9 I based on NMR data ( 19 F, 13 C NMR), where spectral changes are observed when going from free reagents to the complexed mixture, as indicated in Table S1. † The 19 F NMR upeld shis observed in the I-CF 2 -C 3 F 7 are…”

Electron Donor‐Acceptor Complexes in Perfluoroalkylation Reactions

“…Ma, Yu and colleagues have reported a halogen‐bond‐promoted double radical isocyanide insertion with R F –I in the presence of organic bases (Bn 2 NH). The scope of the transformation is depicted in Scheme .…”

Vicinal Difluoroalkylation and Aminosulfonylation of Alkynes under Photoinduced Conditions

“…Based on the above experimental observation and previous reports by Yu and others, we propose a plausible mechanism for the photoinduced vicinal difluoroalkylation and aminosulfonylation of alkynes, which is shown in Scheme . We reason that initially, DABCO⋅(SO 2 ) 2 combines with 2 to generate a halogen‐bonding (XB) adduct A . This XB adduct is reduced by Mes‐Acr + red to form a difluoroalkyl radical in the presence of visible light.…”

“…This result suggests that the reaction proceeds through a radical process. Recently, Yu and co‐workers reported a halogen‐bond‐promoted double‐radical isocyanide insertion with perfluoroalkyl iodides . They demonstrated that fluoroalkyl radicals could be obtained through single‐electron transfer (SET) under visible light.…”