Lawesson's reagent → Ethyl 5-amino-2-(2,6-difluorophenyl)-1,3-thiazole-4-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of the ethyl 2-cyano-2-(2,6-difluorobenzamido)acetate (1 eq) in 10 mL of toluene was added Lawesson reagent. The mixture was stirred at 95° C. for 2 days. Solvents were removed under reduced pressure. The crude residue was purified by flash chromatography (EtOAc:hexanes=1:1) to give the ethyl 5-amino-2-(2,6-difluorophenyl)thiazole-4-carboxylate, which was dissolved in 5 mL of methanol and 5 mL of THF. Then the mixture was added 1M sodium hydroxide (2 eq). The reaction mixture was stirred at room temperature overnight. The reaction was concentrated to remove most of solvents. The residue was extracted with ethyl acetate. The aqueous layer was acidified to pH=4-5 by 1N HCl. The resulting mixture was extracted by ethyl acetate. The organic layer was separated, washed with brine, then dried over anhydrous MgSO4, filtered, and concentrated in vacuo. to give the pure titled compound (34%). LC/MS (m/z): 257.1 (MH+), Rt: 0.61 min.

Provenance & Evidence