TETRABUTYLAMMONIUM FLUORIDE synthesis

Yield:113101-57-8 5.38 g (30%)

Reaction Conditions:

with magnesium;pyridinium chlorochromate in tetrahydrofuran;

Steps:

10 Synthesis of 4-(1'-hydroxy-5'-hexynyl)-2,6-di-tert-butylphenol

Example 10 Synthesis of 4-(1'-hydroxy-5'-hexynyl)-2,6-di-tert-butylphenol A mixture of 3.0 g (120 mmol) of magnesium, 25.7 g (72.0 mmol) of 2,6-di- t -butyl-4-bromo-1-trimethylsiloxybenzene and a few drops of 1,2-dibromoethane in 350 mL THF is heated at reflux for two hours and then is cooled to -78° and to it is added 5.78 g (60.0 mmol) of 5-hexynal (which is prepared from the oxidation of 5-hexyn-1-ol using pyridinium chlorochromate). The reaction mixture is stirred at -78° for 15 minutes and then is allowed to warm to 0°, where it is stirred for an additional 30 minutes. The mixture is poured into sat. NH₄Cl and the aqueous layer is extracted with pentane. The combined organic phase is washed with sat. NaCl and dried (MgSO₄). The crude silylated intermediate is concentrated, dissolved in 300 mL of THF, and treated at room temperature with 28.5 g (90.0 mmol) of tetra- n -butyl-ammonium fluoride trihydrate. After stirring the mixture at 25° for one hour, it is poured into sat. NH₄Cl and the layers are separated. The aqueous portion is extracted with pentane and the combined organic phase is washed with sat. NaCl and then dried (MgSO₄). The concentrate is purified by flash chromatography (10% EtOAc/hexane, R_f=0.16) and recrystallization (hexane) to afford 5.38 g (30%) of the title compound: mp 70-71°; IR (CCl₄) 3620(s), 3310(m), 2960(s), 1430(s), 1160(s), 630(m) cm^min1; ¹H-NMR (CDCl₃)δ(ppm) 1.40(s, 18H), 1.5-2.3(m, 8H), 4.50(t, 1H), 5.15(s, 1H), 7.10(s, 2H); ¹³C-NMRδ18.09, 24.88, 30.19, 34.22, 37.69, 68.51, 74.37, 84.25, 122.46, 135.16, 135.75, 153.04 ppm.

References:

EP251408,1991,B1