Reactions of thioquinanthrene with alkanethiolates. The smiles rearrangement of diquinolinyl sulfides

Reactions of thioquinanthrene 1 with alkali metal alkanethiolates in DMSO or DMF at 70° proceeded through a stage of the S→S type of the Smiles rearrangement (3′‐quinolinethiolate 2A→ 4′‐quinolinethiolate 3A ) to give 4,4′‐dialkylthio‐3,3′‐diquinolinyl sulfides 3 as the final products. When these reactions were carried out at 20° two types of the products were isolated: 3′,4‐dialkylthio‐3,4′‐diquinolinyl sulfides 2 or sulfides 3 depending on the reaction time (1 hour or 7 days). Under acidic conditions 3 ′‐quinolinethiolate 2A underwent intramolecular cyclization to dithiin 1 . Reactions of dithiin 1 with sodium alkanethiolates at 20°, realized as a one‐pot procedure, led to various 3,4‐dialkylthioquinolines 7 . The rearrangement of other 3′‐quinolinethiolates 8A and 11A (the products of the reactions of dithiin 1 with sodium sulfide and sodium methoxide) needed higher temperature (140°).