Trifluoroacetohydrazide → Ethyl 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyridine-7-carboxylate

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Reaktionsschritte

To a solution of ethyl 2-thioxopiperidine-4-carboxylate (5.7 g, 14.95 mmol) in THF (203 mL) was added 2,2,2-trifluoroacetohydrazide (7.8 g, 60.88 mmol) and Hg(OAc)2 (10.71 g, 33.48 mmol) at ice-water. The mixture was stirred at room temperature for 2 hours and heated at 60° C. for overnight, then filtered. Removed the solvent under reduced pressure and the filtrate was concentrated and purified by silica gel column chromatography (PE/EA=3/1) to afford ethyl 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyridine-7-carboxylate (3.5 g, yield 43.8%). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 1.10-1.32 (m, 3H) 2.16 (br. s., 1H) 2.36 (br. s., 1H) 2.93 (br. s., 1H) 3.02-3.39 (m, 2H) 3.90-4.30 (m, 4H).

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