1,2-Diketones were synthesized by the oxidation of corresponding alkynes using air as the oxidant under metal-free conditions upon irradiation of blue light. A cheap and readily available organic dye, eosin Y, was used as the photocatalyst. For various substituents on the aryl ring, the reaction proceeded smoothly to give the dicarbonylation products in moderate to good yields. Some oxidation-sensitive groups, such as formyl and the carbon-carbon double bond, were tolerated under the developed reaction conditions.

Heterocyclic derivatives 4-(sulfonylmethyl)isoquinoline-1,3(2H,4H)-diones were synthesized via a visible-light-promoted reaction of N-alkyl-N-methacryloyl benzamides with sulfonyl chlorides catalyzed by fac-Ir(ppy) at room temperature. With various substituents on the substrates, the reaction proceeded smoothly to give the corresponding products in good to excellent yields. The products could be converted into 3-hydroxy-4-(sulfonylmethyl)-3,4-dihydroisoquinolin-1(2H)-one derivatives by the reduction of NaBH.

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Aryl methyl thioethers and methylene-bridged arylamines were synthesized via highly regioselective para-methylthiolation/bridging methylenation of arylamines using DMSO as the methylthio or methylene source in the presence of NH4I under metal-free conditions. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields.