Rearrangement of Aryl Sulfides in the Presence of Aluminum Chloride

Abstract

Aluminum chloride-catalyzed rearrangement of aryl sulfides leads to thermodynamically controlled equilibrium mixtures at room temperature. On treatment of o-, m- or p-tolyl phenyl sulfide without solvent, the isomer distribution converges to an equilibrium point, 17% ortho, 47% meta and 36% para isomer by intramolecular isomerization. Intermolecular disproportionation by methyl-group exchange to produce diphenyl sulfide and ditolyl sulfide accompanied isomerization. In addition, a new type of aromatic rearrangement, intermolecular disproportionation by exchange of the arylthio group, was found to occur simultaneously giving benzene, toluene and thianthrene derivatives. The rate of this reaction is slower than that of the methyl rearrangement. A similar treatment of α-naphthyl phenyl sulfide gave the β-isomer from intramolecular isomerization and diphenyl sulfide, naphthalene, thianthrene and benzene from intermolecular disproportionation. The mechanisms of the rearrangement of aryl sulfides are discussed.

Oxidative Coupling of Diaryldisulfides by MoCl5 to Thianthrenes

“…[37,38] Cationic 1,2-diaryldisulfides intermediates undergo usually CÀS-bond formations leading to thianthrene architectures. [39] In conclusion, the oxidative treatment of 1,2-diaryldisulfides using MoCl 5 or mixtures thereof with TiCl 4 gives a quick access to thianthrenes in moderate to excellent yields. Due to cationic exchange of the aryl moiety the cross-coupling of mixed disulfides does not proceed cleanly.…”