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To a solution of lithium wire (2.08 g, 300 mmol) in dry tetrahydrofuran (150 ml) was added methyldiphenylsilyl chloride (15.8 ml, 75 mmol) and a catalytic amount of iodine. The reaction mixture was sonicated for 40 min and then stirred overnight at room temperature. The reaction mixture was cooled to −78° C. and 1,1-difluoroethylene (approx. 225 mmol) was passed through the mixture for 30 min. The mixture was stirred at −78° C. for 2 h and then warmed to room temperature. The reaction mixture was quenched with saturated ammonium chloride solution and extracted with cyclohexane (×2). The combined extracts were washed with brine, dried (MgSO4) and concentrated in vacuo. The residue was purified by column chromatography (silica, 1 kg) eluting with hexane, followed by cyclohexane. The appropriate fractions were combined and concentrated to give Preparation 83 (7 g) as a colourless oil.

1. customThe reaction mixture was sonicated for 40 min
2. temperatureThe reaction mixture was cooled to −78° C.
3. stirringThe mixture was stirred at −78° C. for 2 h
4. temperaturewarmed to room temperature
5. customThe reaction mixture was quenched with saturated ammonium chloride solution
6. extractionextracted with cyclohexane (×2)
7. washThe combined extracts were washed with brine
8. dry with materialdried (MgSO4)
9. concentrationconcentrated in vacuo
10. customThe residue was purified by column chromatography (silica, 1 kg)
11. washeluting with hexane
12. concentrationconcentrated
13. customto give