Visible light-induced direct α C–H functionalization of alcohols

Abstract

Considering the synthetic value of introducing active alcoholic hydroxyl group, developing C–H functionalization of alcohols is of significance. Herein, we present a photochemical method that under visible light irradiation, selectfluor can effectively promote the oxidative cross-coupling between alcohols and heteroarenes without the external photocatalysis, achieving the selective α sp3 C–H arylation of alcohol, even in the presence of ether. The N-F activation of selectfluor under blue LEDs irradiation is evidenced by electron paramagnetic resonance (EPR) study, which is the key process for the oxidative activation of α sp3 C–H alcohols. The observed reactivity may have significant implications for chemical transformations.

Diacetyl as a “traceless” visible light photosensitizer in metal-free cross-dehydrogenative coupling reactions

“…Alternatively, Ryu's group employed solar light to activate a decatungstate photocatalyst (TBADT) as a hydrogen atom abstractor, with persulfate salt being added to regenerate the catalyst 12. Other than oxy radical-based oxidants, hydrogen atom abstractors such as nitrogen-centered radical cations from N -hydroxysuccinimide (NHS) and Selectfluor,13 thiyl radicals from thiols,14 iodine/azide-centered radicals from phenyliodine bis(trifluoroacetate) (PIFA)/sodium azide,15 and chlorine radicals generated from dichloromethane (DCM),16 were also feasible under mild reaction conditions.…”

Visible‐Light Photoredox Alkylation of Heteroaromatic Bases Using Ethyl Acetate as Alkylating Agent

“…The strategy of using common organic solvents as radical precursors, however appealing, is only infrequently applied in organic synthesis. [ 1 ] Some examples utilizing toluene, [ 2–7 ] various ether and alcohol, [ 8–19 ] acetonitrile, [ 20–25 ] and N,N ‐dimethylformamide [ 26–30 ] derived radical synthons were reported. The common features of these transformations, besides the radical‐chain mechanism, are the use of strong external oxidants, a stoichiometric amount of transition metals, and elevated temperatures respectively, resulting in narrow substrate scope and poor isolated yields.…”

Visible Light–Driven Cascade Carbon–Carbon Bond Scission for Organic Transformations and Plastics Recycling

“…This concept had been pioneered by Meyer and co‐workers, who demonstrated its potential for chloride and benzyl alcohol oxidation with simultaneous H 2 evolution . Others, including Sun and co‐workers, Meyer and co‐workers, Berlinguette and co‐workers, Reisner and co‐workers, and Lei and co‐workers, have subsequently shown that the gap between AP and radical catalysis can potentially be bridged via the valorization of biomass, functionalization of amines, oxidation of other halides, photo‐electrochemical reduction of CO 2 , and even photoreforming of plastics.…”