Acetic Acid → 2,3-Dichloro-5-(chloromethyl)pyridine

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2,3-dichloro-5-trichloromethylpyridine (36.60 g, 0.139 mol) was added to a flask containing acetic acid (53.50 g, 0.892 mol) and methanol (200 mL). The mixture was cooled to −5° C., and zinc dust (20.01 g, 0.308 mol) was added in small portions at 10 minute intervals. The mixture was stirred mechanically for 4 hours, filtered, and concentrated in vacuo. The residue was dissolved in dichloromethane and washed with brine, followed by saturated aqueous sodium bicarbonate, followed by a second brine wash. The organic phase was dried over magnesium sulfate and concentrated in vacuo to yield 21.55 g (79%) of Preparatory Compound P, 2,3-dichloro-5-(chloromethyl)pyridine, as a yellow liquid (about 65% purity). 1H NMR δ 8.31 (d, 1H, J=2.3 Hz), 7.85 (q, 1H, J=0.4 Hz and J=2.2 Hz), 4.56 (s, 2H). MS (ESI) m/z 199 ([M+4]+, 8), 197 ([M+2]+, 27), 195 ([M]+, 28), 164 (11), 162 (66), 160 (100), 124 (19)

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