Electrochemical decarboxylative C3 alkylation of a wide range of quinoxalin-2(1H)-ones under metal- and additive-free conditions was reported.

An attractive, versatile, and operationally simple, visible-light-induced, transition-metal-free, photocatalyst-free, and oxidant-free trifluoromethylation has been demonstrated. Triflic anhydride (Tf 2 O), being inexpensive and readily available, was chosen as the radical trifluoromethyl source. Thianthrene was used as a recyclable Tf 2 O-activating reagent, and a high-yielding and scalable trifluoromethylation reaction was achieved. Density functional theory and mechanistic studies showed that a free radical homolytic process excited by visible light is involved in this reaction, generating a key trifluoromethyl radical intermediate.

We report herein a mild electrolytic method for efficient C–H alkylation of quinoxalin-2(1H)-ones with organoboron compounds via radical addition to form C–C coupled products.

Progress in photochemical and electrochemical decarboxylation has enabled the rapid construction of functionalized decarboxylated products under extremely mild conditions. The utility of these methods, however, is restricted by the energy of visible-light photons and the chemoselectivity of the electrodes, respectively. Herein, we report a protocol for the photoelectrochemical decarboxylative C−H alkylation of quinoxalin-2(1H)-ones with good reactivity and selectivity. This protocol involves the use of iron, an earth-abundant metal, to catalyze decarboxylation via ligand-to-metal charge transfer. Furthermore, the reactions can be carried out with a 3 V battery as a power supply, revealing the remarkable simplicity and flexibility of this photoelectrochemical protocol. It offers a new paradigm for a convenient, green synthesis of valuable compounds from versatile carboxylic acid building blocks.