Facile aerobic photo-oxidative synthesis of α-diketones from alkynes

Oxidation of Diphenylacetylene in the Presence of Heterogeneous Carbon-Containing Catalysts Based on Palladium, Graphene, and Graphene Oxide

“…As catalysts, we used both a number of composite 2D materials Pd/graphene and Pd/graphene oxide and commercially available samples of palladium supported on carbon black. As mentioned earlier, the main part of the product is formed within 24 h [8][9][10]. In our case, the long heating time is due to the need to ensure the complete conversion of diphenylacetylene (Table 1).…”

“…Despite the fact that the catalytic oxidation of diphenylacetylene has been widely studied [8], much less attention has been paid to the use of heterogeneous catalysts. Earlier it was reported about the use of metals fixed on carbon as catalysts for the oxidation of diphenylacetylene by dimethyl sulfoxide (DMSO) [9] and pyridine N-oxide [10].…”

Synthesis of Substituted Benzils from Diarylalkyne Oxidation

“…In the course of photo-oxidation studies, Itoh and coworkers found that substituted diarylalkynes were oxidized to the corresponding benzils using O 2 and hν in the presence of MgBr 2 •Et 2 O. 26 This method, which uses molecular oxygen as the oxidant and an easy handle bromine source MgBr 2 •Et 2 O (1 equiv) is of interest from the viewpoint of green chemistry. Moreover, the oxidation reactions were achieved at room temperature and tolerated a variety of substituents (EDG and EWG) and heterocycles on the alkyne triple bond such as, for example, a pyridine ring.…”

“…Moreover, the presence of a pyridine ring was tolerated, but the yield of the resulting 1,2-diketone was low (32-33%) regardless of the position of the nitrogen atom in the ring. The proposed mechanism 26 for this photo-oxidation reaction is depicted in Scheme 11. In the presence of O 2 under irradiation, a bromide ion is converted into a bromide radical which adds to the diarylalkyne to generate a vinylradical of type I.…”

“…lytic systems were efficient with electron-rich (entries 1-10) or electron-poor arylalkynes (entries [11][12][13][14][15][16][17][18][19][20], as well as with push-pull and pull-pull diarylalkynes (entries [21][22][23][24][25][26][27].…”