From triarylbismuth difluorides and organometallic reagents

From triarylbismuth difluorides and organometallic reagents (method 

Treatment of triarylbismuth difluorides with organosilicon reagents, such as silyl enol ethers [94JCS(P1)1739], siloxycyclopropanes [95JCS(P1)2543], ketene silyl acetals [99JOC6924, 95JCS(P1)2543] or allylsilanes 

To a dichloromethane (5 ml) solution of triphenylbismuth difluoride (478 mg, 1 mmol) was added dropwise boron trifluoride diethyl etherate (0.12 ml, 1 mmol) at 0°C under argon. After stirring for 1 h, 3,3-dimethyl-2-trimethylsiloxy-l-butene (172 mg, 1 mmol) was introduced and the resulting mixture was stirred for 10 h at room temperature. Evaporation of the solvent under reduced pressure left an oily residue, which was crystallized from ether-dichloromethane (2 1) to give the bismuthonium tetrafluoroborate (601 mg, 96%) as colorless crystals (m.p. 143-145°C) [94JCS(P1)1739]. 

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