Hydrochloric Acid → Ethyl 2-(2-cyclohexylacetylamino)-4,5,6,7-tetrahydrobenzthiazol-4-carboxylate

참여 물질

반응 단계

Oxalyl chloride (3.10 g, 24.42 mmol) was added to a solution of cyclohexylacetic acid (2.31 g, 16.24 mmol) in DCM (10 mL). The reaction mixture was stirred over a period of two hours at RT under a blanket of nitrogen. The solvent was removed in vacuo, toluene (50 mL) was added and the solvent was again removed. The residue was dissolved in DCM (50 mL) and the resultant solution was slowly added dropwise to a solution of ethyl 2-amino-4,5,6,7-tetrahydrobenzthiazole-4-carboxyate hydrobromide (E) (5.0 g, 16.3 mmol) in pyridine (25 mL) under a blanket of nitrogen. The reaction mixture was stirred for one hour at 0° C. and then overnight at RT. DCM (300 mL) and hydrochloric acid solution (3N in water) were added, the phases were separated, and the aqueous phase was shaken out with DCM (300 mL). The combined organic phases were dried over Na2SO4 and the solvent was removed in vacuo. Following purification by column chromatography (SiO2, EtOAc/heptane 1:2), the residue yielded 4.9 g (86% of theory) of the desired product ethyl 2-(2-cyclohexylacetylamino)-4,5,6,7-tetrahydrobenzthiazol-4-carboxylate (F).

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