n- (CAS NO.: ) could be produced through the following synthetic routes.

A. Trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate (CAS NO.: ). All glassware is oven-dried for about 1 hr prior to use. A 1-L, three-necked, round-bottomed flask is equipped with a magnetic stirrer, addition funnel with a nitrogen (N₂) inlet, and water-cooled condenser with gas outlet. The gas outlet is connected by Tygon tubing to an empty 500-mL back-up trap, and then to an inverted 75-mm glass funnel outlet positioned just above a 1-L beaker containing 75 g of sodium bicarbonate (NaHCO₃) in 500 mL water (to neutralize HCl and chlorotrimethylsilane from the reaction vessel). The flask is charged with 150 g of 2-fluorosulfonyl-2,2-difluoroacetic acid (0.84 mol). Then, with a slow N₂ flow and cooling with an ice bath, 363 g of chlorotrimethylsilane (3.2 mol) is added dropwise with stirring over a 2 hr period. Upon completion of the addition, the mixture is allowed to warm to room temperature and is stirred with N₂ bubbling for 24 hr. The product mixture is distilled to give 175 grams (83%) of trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate (bp 52°C at 15 mm).

B. n-Butyl 2,2-difluorocyclopropanecarboxylate (CAS NO.: ). A 500-mL, round-bottomed, three-necked flask is fitted with a magnetic stirrer, condenser, addition funnel, gas dispersion tube extending to the bottom of the flask, and gas outlet with a paraffin oil bubbler. The flask is charged with 200 mL of , 0.4 g of sodium fluoride (0.06 eq), and 20 g of n-butyl acrylate (0.156 mol). The solution is heated to reflux and slow N2 bubbling is initiated with stirring for 1 hr. Trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate (62.5 g, 0.31 mol, 1.6 eq) is added dropwise. The mixture is heated for 8 hr, then cooled and filtered under vacuum filtration through a Celite pad. Toluene is removed by simple distillation at atmospheric pressure, and the residue distilled at reduced pressure to obtain 15.4 g of n-butyl 2,2-difluorocyclopropanecarboxylate (55%) (bp 99-101°C at 58 mm) as a colorless liquid.

Notice: Trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate should be handled with care. Skin contact, which will cause painful burns and blistering, should be avoided. If such contact occurs, the affected area should be washed thoroughly with water and with sodium bicarbonate solution.