Categories: C-S Bond Formation >
Synthesis of thiophenols
Readily available Na2S·9H2O as sulfur source and a catalystic amount of 1,2-ethanedithiol enable a copper-catalyzed direct and effective synthesis of aryl thiols from aryl iodides in very good yields.
H. Xue, B. Jing, S. Liu, Y. Chae, Y. Liu, Synlett, 2017, 28, 2272-2276.
A CuI-catalyzed coupling reaction of aryl iodides and sulfur powder takes place in the presence of K2CO3 at 90°C in DMF as solvent. The coupling mixture is directly treated with NaBH4 or triphenylphosphine to afford aryl thiols in good to excellent yields. A wide range of substituted aryl thiols that bear methoxy, hydroxyl, carboxylate, amido, keto, bromo, and fluoro groups can be synthesized.
Y. Jiang, Y. Qin, S. Xie, X. Zhang, J. Dong, D. Ma, Org. Lett., 2009, 11, 5250-5253.
CuI-nanoparticles catalyze a selective synthesis of phenols, anilines, and thiophenols from aryl halides in the absence of both ligands and organic solvents. Anilines were formed selectively with ammonia competing with hydroxylation and thiophenols were generated selectively with sulfur powder after subsequent reduction competing with hydroxylation and amination.
H.-J. Xu, Y.-F. Liang, Z.-Y. Cai, H.-X. Qi, C.-Y. Yang, Y.-S. Feng, J. Org. Chem., 2011, 76, 2296-2300.
The conversion of primary carbamates into thiols in the presence of phosphorus pentasulfide (P4S10) in refluxing toluene is an indirect route for the conversion of alcohols that may be useful in the total synthesis of compounds containing a thiol functionality.
C. K. Maurya, P. K. Gupta, Synlett, 2017, 28, 1649-1651.
A trifluoroacetic-acid-mediated desulfurilative sulfonylthiolation of arenes with SS-morpholino dithiosulfonate is based on selective activation of the morpholino group over the tosyl group of the doubly transformable sulfur surrogate. The reaction proceeds through electrophilic aromatic substitution followed by sulfur extrusion.
K. Kanemoto, K. Furuhashi, Y. Morita, T. Komatsu, S.-i. Fukuzawa, Org. Lett., 2021, 23, 1582-1587.
An electrochemical approach toward rearrangement of O-aryl thiocarbamates to S-aryl thiocarbamates at room temperature requires only catalytic amounts of electric charge. The electrolysis can be carried out with the simple equipment under galvanostatic conditions in an undivided cell. In a microflow reactor, almost quantitative yields can be achieved without using a supporting electrolyte.
T. Broese, A. F. Roesel, A. Prudlik, R. Francke, Org. Lett., 2018, 20, 7483-7487.