반응 #537175

반응 방정식

thiocarbamate

ethyl 3-[(aminocarbonothioyl)amino]benzoate

ethyl 2-amino-1,3-benzothiazole-7-carboxylate hydrobromide

ethyl 2-amino-1,3-benzothiazole-5-carboxylate hydrobromide

→

ethyl 2-amino-1,3-benzothiazole-7-carboxylate

수율 95.0%

용매

chloroform

chloroform

acetic acid

반응 조건

후처리

1. 1
   온도was heated at 70° C. for 4 h
2. 2
   온도to cool to room temperature
3. 3
   온도maintained for an additional 13 h
4. 4
   기타The volatiles were removed under reduced pressure
5. 5
   workup.ADDITIONthe solid residue was suspended in a mixture of chloroform (10 mL) and acetone (10 mL)
6. 6
   기타The product was isolated by filtration
7. 7
   세척washed successively with acetone (5 mL) and hexanes (10 mL)
8. 8
   기타dried in a vacuum oven
9. 9
   기타thus providing the product in 95% yield
10. 10
    기타This product was partitioned between saturated aqueous solution of sodium bicarbonate (25 mL)
11. 11
    workup.ADDITIONa mixture of ethyl acetate (70 mL) and tetrahydrofuran (30 mL)
12. 12
    기타The organic layer was separated
13. 13
    건조dried over anhydrous sodium sulfate
14. 14
    농축concentrated
15. 15
    기타The residue was crystallized form ethyl acetate

실험 절차

A solution of thiocarbamate (12.2 mmol) in chloroform (10 mL) was added dropwise over a period of 40 min to a vigorously maintained mixture of ethyl 3-[(aminocarbonothioyl)amino]benzoate (5.78 mmol), glacial acetic acid (10 mL) and chloroform (10 mL). The mixture was maintained 30 min at rt and then was heated at 70° C. for 4 h. The mixture was allowed to cool to room temperature and maintained for an additional 13 h. The volatiles were removed under reduced pressure and the solid residue was suspended in a mixture of chloroform (10 mL) and acetone (10 mL). The product was isolated by filtration, washed successively with acetone (5 mL) and hexanes (10 mL), and dried in a vacuum oven, thus providing the product in 95% yield as a mixture of ethyl 2-amino-1,3-benzothiazole-7-carboxylate hydrobromide and ethyl 2-amino-1,3-benzothiazole-5-carboxylate hydrobromide in a ratio of 95/5, respectively. This product was partitioned between saturated aqueous solution of sodium bicarbonate (25 mL) and a mixture of ethyl acetate (70 mL) and tetrahydrofuran (30 mL). The organic layer was separated, dried over anhydrous sodium sulfate and concentrated. The residue was crystallized form ethyl acetate, thus providing pure ethyl 2-amino-1,3-benzothiazole-7-carboxylate. 1H NMR (500 MHz, Me2SO-d6) δ 1.35 (t, J=7.5, 3H), 4.36 (q, J=7, 2H), 7.35 (t, J=7.5, 1H), 7.57 (d, J=7, 1H), 7.61 (bs, 2H), 7.65 (d, J=8, 1H); MS (EI) m/z 223 (M++1).

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