Intramolecular Aromatic 1,5-Hydrogen Transfer in Free Radical Reactions III. Reactivity of Diaryl Ketones, Ethers, Thioethers, Sulfoxydes, and Sulfones. An Experimental and Theoretical Study

Experiments show that free radical hydrogen shift is significant in the Pschorr cyclization of diphenyl ethers (X = O) and thioethers (X = S) and does not take place with sufoxides (X = SO) and sulfones (X = SO2). DFT calculations of the product ratios, activation energies, rate constants for H-transfers, and ring-closings at the UB3PW91/6-31G(d,p) level are in excellent agreement with the experimental results reported here and elsewhere in the literature.