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Synthesis of isothiocyanates
A facile and general protocol for the preparation of isothiocyanates from alkyl and aryl amines relies on a tosyl chloride mediated decomposition of a dithiocarbamate salts that are generated in situ by treatment of amines with carbon disulfide and triethylamine. Vairous alkyl- and arylisothiocyanates have been prepared in good yield.
R. Wong, S. J. Dolman, J. Org. Chem., 2007, 72, 3969-3971.
In the presence of trifluoromethanesulfonyl chloride, triphenylphosphine, and sodium iodide, a broad range of thiocarbamyl fluorides and isothiocyanates can be synthesized from secondary and primary amines in good yields, respectively. The reactions offer good functional group compatibility.
J. Wei, S. Liang, L. Jiang, W. Yi, J. Org. Chem., 2020, 85, 12374-12381.
A two-step, one-pot reaction of primary amines or their salts with carbon disulfide, followed by reaction of the intermediate dithiocarbamates with T3P provides isothiocyanates in good yields. T3P® (propane phosphonic acid anhydride) acts as an efficient desulfurating agent.
Ł Janczewski, A. Gajda, S. Frankowski, T. M. Goszczyński, T. Gajda, Synthesis, 2018, 50, 1141-1151.
Reactions of thiocarbonyl fluoride derived from CF3SiMe3, elemental sulfur, and KF with secondary amines provides a wide variety of thiocarbamoyl fluorides in good yields at room temperature in THF, whereas the reaction with primary amines gives isothiocyanates. The two reactions show broad substrate scope and good functional group tolerance. Moreover, AgSCF3 can be used as an alternative.
L. Zhen, H. Fan, X. Wang, L. Jiang, Org. Lett., 2019, 21, 2106-2110.
A facile and efficient synthesis of isothiocyanates involves the reaction of amines with phenyl chlorothionoformate in the presence of solid sodium hydroxide by either a one-pot process or a two-step approach. The one-pot process is useful for preparing alkyl and electron-rich aryl isothiocyanates, whereas the two-step approach is more versatile.
Z.-Y. Li, H.-Z. Ma, C. Han, H.-T. Xi, Q. Meng, X. Chen, X.-Q. Sun, Synthesis, 2013, 45, 1667-1674.