(3,3-Difluoroallyl)trimethylsilane (CAS no.: 40207-81-6), which is also known to us as Silane, (3,3-difluoro-2-propenyl)trimethyl-, could be produced through the following synthetic routes.

A. (1,3-Dibromo-3,3-difluoropropyl)trimethylsilane. A 250-mL pressure tube equipped with a magnetic stirring bar is charged with vinyltrimethylsilane (20 g, 30.8 mL, 0.20 mol), ethanolamine (6.11 g, 6.04 mL, 0.10 mol), dibromodifluoromethane (83.9 g, 36.5 mL, 0.4 mol), copper(I) chloride (0.18 g, 1.8 mmol), and tert-butyl alcohol (15 mL). The tube is sealed and stirred for 20 hr in an oil bath at 90°C. The reaction mixture is combined with that from another run at the same scale and diluted with 40 mL of hexane (the mixture separates into a cloudy supernatant and a brown resin). The hexane layer is separated and the resinous precipitate extracted with two 20-mL portions of hexane. The combined solutions are filtered through a bed of silica gel on a 60-mL fritted glass funnel and the resulting clear filtrate is concentrated by rotary evaporation using a water aspirator. The crude material is fractionally distilled to afford 71.9–78.3 g (58–61%) of the dibromide as a colorless oil, bp 78–79°C (12 mm) [lit.2 bp 95°C (25 mm)].

B. (3-Bromo-3,3-difluoropropyl)trimethylsilane. A 1-L, four-necked flask is equipped with a mechanical stirrer, thermometer, Claisen adapter, septum inlet, reflux condenser (the top of which is connected to a calcium chloride drying tube), and a solid addition funnel. The flask is charged with (1,3-dibromo-3,3-difluoropropyl)trimethylsilane (78.3 g, 0.25 mol), and anhydrous dimethyl sulfoxide (200 mL), and the solid addition funnel is charged with sodium borohydride (11.5 g, 0.30 mol). The stirred solution is warmed to 80°C, and sodium borohydride is added at a rate sufficient to maintain a reaction temperature of 80–90°C. Toward the end of the addition, an additional portion of dimethyl sulfoxide (200 mL) is added via syringe to lower the viscosity of the reaction mixture. After the addition is complete, the mixture is cooled in an ice-water bath, diluted with 100 mL of pentane, and cautiously quenched with 12 M hydrochloric acid until no further gas evolution occurs. The mixture is transferred to a separatory funnel and washed with three 100-mL portions of 5% brine. The pentane extract is dried over calcium chloride and the solvent removed through a 15-cm Vigreux column. Further fractionation yields 41.5 g (72%) of 3-bromo-3,3-difluoropropyltrimethylsilane, bp 139–141°C.

C. (3,3-Difluoroallyl)trimethylsilane. A 100-mL, three-necked, round-bottomed flask is equipped with a magnetic stirrer, short-path distillation head, and an electric heating mantle. The flask is charged with 30.99 g (0.13 mol) of (3-bromo-3,3-difluoropropyl)trimethylsilane and 29.1 g (0.19 mol) of 1,8-diazabicyclo[5.4.0]undec-7-ene (). Stirring and gradual heating are begun and the reaction mixture becomes thick with precipitate. The product distilling from the mixture is collected from 80–100°C giving 11.88 g of colorless liquid.

Additional product is obtained by extractive workup of the residue. The cooled residue is acidified by adding 50 mL of 3 N hydrochloric acid and the resulting solution is extracted with 50 mL of pentane. The pentane layer is washed with 2 × 50 mL of water, dried over sodium sulfate, filtered and concentrated at 35°C under ca. 30 mm vacuum. The remaining liquid is distilled using a short-path distillation head to afford an additional 1.77 g of product (bp 86–95°C). The combined product, weighing 13.65 g (70% yield), has a purity of 85–90% based on NMR and capillary GC analysis.