Tris(phenylthio)methane

Experimental procedure: Conjugate addition of [tris(phenylthio)methyl]lithium [prepared from tris(phenylthio)methane (3.746 g, 11.0 mmol) and n-buthyllithium (1.6 mol/L solution, 6.96 mL, 11.0 mmol)] to 2-cyclohexanone (0.968 mL, 110 mmol) is carried out at -78 °C in THF (160 mL). NMP (40 mL) is added, and the reaction flask is warmed to -30 °C. After 5 min, 1-bromo-2-methyl-2-propene (2.02 g, 15 mmol) in THF (15 mL) is added. The reaction mixture is stirred at -30 °C for 1 h and room temperature overnight. The reaction flask is placed in an ice bath, and silver triflate (3.08 g, 12 mmol) is added in one portion. Immediate formation of a yellow precipitate indicates that the cyclization is completed. The reaction flask is warmed to room temperature, and excess silver triflate (6.2 g, 24 mmol) is added. The black slurry is stirred for an additional 10 min, and the organic layer is filtered off. The organic layer is washed with H₂O (2 x 30 mL) and brine and dried over MgSO₄. Filtration and solvent evaporation give a yellow oil, which is purified by flash chromatography (hexane : Et₂O = 95 : 5) to obtain the tetrasubstituted benzene 4 (1.50 g, 56% yield).