tert-Butyldimethylsilyl chloride → (Trifluoromethyl)t-butyldimethylsilane

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Into a dry 250 mL Schlenk flask under an argon atmosphere, was added 5.14 g Mg turnings (214 mmol) and 32.3 g (214 mmol) t-butyldimethylsilyl chloride in 150 mL DMF at −30° C. Subsequently, 15.0 g (71.4 mmol) of 1 in 10 mL DMF was added slowly via a syringe. The reaction mixture was stirred at room temperature at −30° C. for 1 h, and then at room temperature for another 2 h until all the starting material was consumed (19F NMR showed that the conversion was 75%). The reaction mixture was washed with ice water, followed by extraction with pentane (30 mL×4 ). Combined pentane phase was further washed carefully with cold 98% sulfuric acid (20 mL×4) to remove most of the siloxane and silanol. Then the pentane phase was washed with cold NaHCO3 aqueous solution three times until pH paper indicated neutral pH. The pentane phase was dried over MgSO4 and solvent evaporated to give a crude product that was fractionally distilled to give 7.46 g colorless liquid 16 (95° C./410 Torr), which turned to a transparent crystalline solid at room temperature (m.p. 52˜54° C., sublimes), yield 57%. 1H NMR (500 MHz, CDCl3): δ0.20 (s, 6H); 0.99 (s, 9H). 13C NMR (125 MHz, CDCl3): δ−8.8; 16.0; 26.0; 132.0 (q, 1JC-F=323.8 Hz, CF3). 19F NMR (470 MHz, CDCl3): δ−61.8. 29Si NMR (99 MHz, CDCl3): δ8.4 (q, 1JSi-F=32.8 Hz). GC-MS (m/z): 184 (M+), 127 (M+-tBu), 115 (M+-CF3), 99 (M+-CF3—CH3), 57 (tBu+). High-resolution GC-MS (EI): m/z calculated for C7H15F3Si (M+) 184.0895, found 184.0943.

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