By using tetrabutylammonium fluoride as the catalyst, the synthesis of unsymmetrical diaryl thioethers could be easily achieved in high yields via a mild nucleopilic aromatic substitution reaction of aryl fluorides and phenylthiotrimethylsilane.
Optimized conditions are elaborated for each type of substrates to afford a broad spectrum of title compounds including fluoro derivatives with biological significance. -(LIU, C.; ZANG, X.; YU, B.; YU*, X.; XU, Q.; Synlett 2011, 8, 1143-1148, http://dx.doi.org/10.1055/s-0030-1259959 ; Coll. Chem. Mater. Eng., Wenzhou Univ., Wenzhou, Zhejiang 325035, Peop. Rep. China; Eng.) -Mais 37-074
General. Unless otherwise noted, reactants and catalyst were purchased and used without further purification. Reactions were carried out in air directly using commercial solvents and monitored by TLC and/or GC-MS. Products were purified by column chromatography on silica gel using petroleum ether and ethyl acetate as eluent. 1 H NMR and 13 C NMR spectra were measured on a Bruker Avance-III 500 instrument (500 MHz for 1 H and 125.4 MHz for 13 C NMR spectroscopy) or a Bruker Avance 300 instrument (300 MHz for 1 H and 75 MHz for 13 C NMR spectroscopy) using CDCl 3 as the solvent with tetramethylsilane (TMS) as the internal standard. Mass spectra were measured on a Shimadzu GC-MS-QP2010 Plus spectrometer (EI). HRMS (EI) analysis was performed by the Analytical Center at the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences. Typical Procedure for Microwave-Promoted TBAF-Catalyzed S N Ar Reaction of ArSTMS and Aryl Fluorides. The mixture of phenylthiotrimethylsilane 1a (0.218 g, 1.2 mmol, 1.2 equiv.), p-nitrophenyl fluoride 2a (0.141 g, 1.0 mmol), and TBAF (2.61 mg, 1 mol%) in acetonitrile (2 mL) was placed in a microwave oven flask under air and then stirred at room temperature (~25 o C) under microwave irradiation (600 w) for 5 h and the reaction was monitored by TLC and/or GC-MS. Solvent was then evaporated under reduced pressure and the residue purified by flash column chromatography on silica gel to give 97% yield of 3aa. An XH-100A microwave synthesis/extraction instrument, made by Beijing Xiang Hu Science and Technology Development Co. Ltd., was employed in above microwave irradiation reactions. PhS NO 2 (4-Nitrophenyl)phenylthioether (3aa).
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