Methyl iodide → 9-Methyl-2,7-bis(trimethylsilyl)-9H-fluorene

Participants

Reaction Steps

To a solution of 1.0 g of 2,7-bis(trimethylsilyl)fluorene in 15 mL of dry ether was added dropwise 2.8 mL of 1.3 M n-butyllithium at 0° C. The mixture was stirred at room temperature for 3 hours, cooled to 0° C., and treated with a solution of 0.25 mL of methyl iodide in 5 mL of dry ether over a period of 5 minutes. The mixture was stirred at room temperature for 8 hours and washed with 2% Na2S2O3 (10 mL) and water (2×10 mL). The pooled aqueous layer was extracted with ether (2×15 mL). The combined organic extracts were dried over MgSO4 and the solvent was evaporated under reduced pressure to give 1.03 g (98.7%) of the crude 2,7-bis(trimethylsilyl)-9-methylfluorene as a yellow oil which was chromatographed on silica gel (230-400 mesh, 2×40-cm packed column) with an eluant consisting of Skelly B--dichloromethane (6:1) to give 0.78 g (74.7%) of the crude hydrocarbon as a colorless oil. Crystallization from 95% ethanol gave 0.69 g (66.1%) of the pure 2,7-bis(trimethyl-silyl)-9-methylfluorene as white needles, m.p. 107°-108.5° C.; 1H NMR (CDC13): δ 0.34 (s, 18H, SiMe3), 1.58 (d, 3H, CH3), 3.96 (q, 1H, CH), 7.40-7.90 (m, 6H, aryl).

Provenance & Evidence