Radical phthalimidation of aromatic compounds by photolysis of N-tosyloxyphthalimide: a route to primary aromatic amines

Abstract

N-Tosyloxyphthalimide (3) is a stable solid readily prepared from N-hydroxyphthalimide and toluene-p-sulphonyl chloride. It undergoes photolysis at room temperature, in Pyrex, in the presence of aromatic compounds (PhX) to give 12–100% yields of the corresponding N-arylphthalimides (4; X = H, MeO, Me, Bu^t, Ph, or Cl); hence, via hydrazinolysis, the corresponding primary arylamines can be obtained. Measurements of isomer ratios, rate ratios, and hence partial rate factors for the reaction show that phthalimido-radicals rather than nitrenium ions are involved. This is confirmed by comparison with corresponding data obtained from thermolysis of N-chlorosulphonylphthalimide in the same aromatic solvents.