Trimethylsilyldiazomethane → Methyl 3,3,3-trifluoro-2,2-dimethylpropanoate

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Reaction Steps

Reaction was carried out in two separate batches, employing 5 g of 3,3,3-trifluoro-2,2-dimethylpropionic acid in each batch. To a stirred solution of 3,3,3-trifluoro-2,2-dimethylpropionic acid (5 g, 32 mmol) in anhydrous dichloromethane (20 mL) at 0° C. (under an argon atmosphere), was added dropwise a solution of (trimethylsilyl)diazomethane (18 mL of a 2M solution in diethyl ether, 35 mmol) (gas evolution observed). The resulting yellow solution was allowed to warm to rt and stirred for a further 48 h. An additional 5 mL of 2M (trimethylsilyl)diazomethane solution (10 mmol) was added, and stirring continued for a further 5 h whereupon a further 6 mL of 2 M (trimethylsilyl)diazomethane solution (12 mmol) was added. After stirring for a further 15 h, the reaction mixture was concentrated in vacuo (keeping bath temperature below 30° C.). The resulting oil was redissolved in diethyl ether (200 mL), washed with saturated sodium hydrogencarbonate solution (100 mL), separated, and dried over MgSO4. Filtration followed by concentration in vacuo (keeping bath temperature below 30° C.) gave crude product. Crude product from both batches were combined to afford crude methyl 3,3,3-trifluoro-2,2-dimethylpropanoate (7.69 g) as a yellow oil which was taken on without further purification. 1H NMR (300 MHz, CDCl3) δ 3.86 (s, 3H), 1.40 (s, 6H).

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