Hexane → 2,2-Difluoro-2-pyridin-2-ylethyl 4-methylbenzenesulfonate

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2,2-Difluoro-2-pyridin-2-ylethanol (H) from step 2 (10 g) was dissolved in 100 mL of MDC, 19 g of TEA was added, then the RM was cooled to 0-10° C. To the cooled solution, 16.77 g of pTsCl was added over a period of 1 hour and stirred for 24 hours at RT. The RM was then quenched with 100 mL of 10% sodium bicarbonate solution and the organic layers were separated. The aqueous layer was extracted with (100 mL×3) MDC. The organic layer was combined and washed with 10% sodium bicarbonate (150 mL), followed by water (150 mL) and a brine solution (150 mL). The organic layer was distilled under vacuum. The crude mass obtained was treated with 30 mL of hexane with cooling and filtered, resulting in pure tosylate. (Weight=15 g, Yield=76.2%). It should be noted that the above process may be followed for the preparation of other sulfonates such as methanesulfonate by using the corresponding sulfonyl chloride (e.g. methanesulfonyl chloride). The compound thus prepared is used in the preparation of a compound of formula (K2). 1H-NMR (CDCl3, δ, ppm): 400 MHz: 2.45 (s, 3H), 4.63-4.69 (t, 2H), 7.31-7.33 (d, 2H), 7.36-7.39 (t, 1H), 7.63-7.65 (d, 1H), 7.71-7.73 (d, 2H), 7.79-7.82 (t, 1H), 8.55-8.54 (d, 1H); MS m/z: 314 (M+1).

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