Trimethylsilylacetylene → 2-(1-Methyl-3-trimethylsilanyl-prop-2-ynyl)-phenol

Participants

Reaction Steps

A solution of 18.5 grams (188 mmol, 2.2 eq) of trimethylsilylacetylene in 90 mL of dry THF was stirred under argon in a dry 500 mL round bottom flask at room temperature. To this solution was then slowly added 171 mL (171 mmol of a 1.0 M solution in THF, 2.0 eq) of ethyl magnesium bromide. The colorless solution was stirred for 2 hours. In a separate dry 1 L round bottom flask; 19.0 grams (85.5 mmol, 1.0 eq) of aldehyde 4 was dissolved in 270 mL of dry THF under argon. This solution was then cooled to −78° C. in an acetone/dry ice bath at which time 56.0 mL (89.7 mmol of a 1.6 M solution in Et2O, 1.05 eq) of methyl lithium was added with a syringe pump (2.5 mL/minute) and stirred at −78° C. for 25 minutes. The dry ice bath was then removed and the solution was stirred for 10 minutes at room temperature. The initial Grignard solution from the first flask was then added via cannula to the room temperature 1 L flask and the combined solutions were stirred for 2 hours under argon at room temperature. The solution was then diluted with Et2O and washed sequentially with 1.0 M HCl, saturated NaHCO3, brine and dried over MgSO4. The resulting colorless oil could be purified via silica gel chromatography (hexanes/EtOAc) or used directly in the subsequent step, Rf 0.29 (7:1 hexane:EtOAc). 1H-NMR (500 MHz, CDCl3): 7.16 (m, 2H), 6.89 (m, 2H), 6.18 (s, 1H), 3.89 (q, J=7.1 Hz, 1H), 1.51 (d, J=7.3 Hz, 3H), 0.20 (s, 9H). 13C-NMR (500 MHz, CDCl3): 154.02, 128.56, 128.41, 128.26, 121.15, 117.19, 108.45, 88.53, 29.24, 22.58, 0.16. IR (cm−1): 3447 (b), 2959 (w), 2163 (w), 1591 (w), 1453 (m), 1249 (s), 843 (s), 754 (s). HRMS (EI) calcd. for C13H18OSi: 218.1127. found: 218.1129.

Provenance & Evidence