Solvent-promoted photochemical carbonylation of benzylic C-H bonds under iron catalysis.

This paper describes the iron-catalyzed photochemical carbonylation of benzylic C-H bonds resulting in the synthesis of various aryl ketones. Using 5 W blue LED irradiation, the reactions proceed smoothly in the presence of 2 mol% of FeBr3 in MeOH at 35 °C. The catalytic system could be extended for the oxidation of silane, thioether, and phosphine into silenol, sulphoxide, and phosphoxide, respectively. A mechanistic study suggests that a hydrogen bond-stabilized iron-hydroperoxo species is the reactive intermediate. It is shown that the reaction proceeds via a four-electron-transfer pathway, and a benzylic cation seems to be the crucial reactive species. The method is applied for the synthesis of pomalyst, haloperidol, melperone, and lenperone.

Photoinduced Radical Sulfinylation of C(sp3)-H Bonds with Sulfinyl Sulfones.

A direct C(sp3)-H sulfinylation reaction of alkanes with sulfinyl sulfones via decatungstate photocatalysis is reported. The sulfinyl sulfones generated in situ from sulfinates in the presence of an acylating reagent were able to trap the alkyl radicals that were produced via the photoinduced direct hydrogen atom transfer of alkanes, leading to a range of sulfoxides. This radical sulfinylation process provides an efficient and concise method for the synthesis of sulfoxides from abundant alkanes under mild conditions. Using the same strategy, aldehydes can also be transferred to the corresponding sulfoxides via decarbonylative sulfinylation.

Iron/photoredox dual catalysis for acyl nitrene-based C-O bond formation towards phthalides.

This paper describes iron/photoredox dual-catalyzed acyl nitrene formation and the use of acyl nitrene in constructing various C-O bonds towards phthalides. The developed reaction starts from N-methoxyl-2-alkylbenzamides. Mechanism surveys suggest the reaction involves iron nitrene-based hydrogen atom abstraction (HAA), radical-polar crossover and O-nucleophilic SN1. Distinctively, the often-reported radical rebound in previous publications is not observed. The reaction represents the first example on acyl nitrene-based synthesis of phthalides. Moreover, it also serves as a supplement for the synthesis of marketed medicines such as 3-butylphthalides (NBP), thalidomide, Pomalyst and Otezia.