Transition-Metal-Free Arylations via Photogenerated Triplet 4-Alkyl- and 4-Trimethylsilylphenyl Cations

The irradiation in protic solvents of 4-chloroalkylbenzenes and 4-chlorophenyltrimethylsilane caused the heterolytic cleavage of aryl chlorine bonds to give the corresponding triplet phenyl cations. These were exploited for transition-metal-free arylation reactions under mild conditions to give allylbenzenes, gamma-benzyl lactones, 3-arylacetals (ketals), and biaryls in moderate to good yields. The path followed was supported by DFT calculations at the UB3LYP/6-311+G(2d,p) level.