Thiobenzoic acid (TBA) can serve as a single-electron reducing agent under photoirradiation from a blue light-emitting diode, in the presence of appropriate electron acceptors, and the resulting sulfur-centered radical species undergoes hydrogen atom abstraction. This dual-role catalysis by TBA enables regioselectivie Cα−H arylation of benzylamines, benzyl alcohols, and ethers, as well as dihydroimidazoles, with cyano(hetero)arenes in good yield, without the need for a transition-metal photocatalyst and/or synthetically elaborated organic dyes.

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The trifluoromethylation of various aromatic compounds with Umemoto reagent II (2,8-difluoro-5-(trifluoromethyl)-5H-dibenzo[b,d]thiophen-5-ium triflate) proceeded in moderate to good yields under simple photo-irradiation conditions without any catalyst, additive, or activator. UV-Vis and NMR spectral analyses indicated that pre-formation of an electron donor-acceptor complex between the trifluoromethylating reagent and the substrate, as proposed in previous studies, is not essential for generation of the trifluoromethyl radical. Instead, the radical appears to be formed by simple photo-activation of the Umemoto reagent.

A concise approach for the synthesis of the 5'-carba analogs of nucleoside 5'-phosphates from 2'-deoxy-5'- O-phthalimidonucleosides by a visible-light-mediated deformylative 1,4-addition was developed. This method enabled rapid and facile generation of 4'-carbon radicals of nucleosides. Moreover, this synthetic strategy was applicable to the 5'-carba analogs of nucleoside 5'-phosphates as well as other 5'-carba nucleosides bearing methoxycarbonyl, cyano, and N-methylsulfamoyl groups.

Direct generation of a benzyl radical by C-H bond activation of toluenes and the addition reaction of the resulting radical to an electron deficient olefin were developed. The reaction of dimethyl fumarate with toluene in the presence of Et(3)B as a radical initiator at reflux afforded 2-benzylsuccinic acid dimethyl ester in good yield.