反应详情

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).

1. customThe solvent was removed in vacuo, toluene (50 mL)
2. additionwas added
3. customthe solvent was again removed
4. dissolutionThe residue was dissolved in DCM (50 mL)
5. stirringThe reaction mixture was stirred for one hour at 0° C.
6. customovernight
7. customat RT
8. customthe phases were separated
9. stirringthe aqueous phase was shaken out with DCM (300 mL)
10. dry with materialThe combined organic phases were dried over Na2SO4
11. customthe solvent was removed in vacuo
12. custompurification by column chromatography (SiO2, EtOAc/heptane 1:2)