Ethyl 2-amino-1,3-benzothiazole-7-carboxylate hydrobromide → Ethyl 2-aminobenzo[d]thiazole-7-carboxylate

HRID 33755Notes

Reaction equation

HRID 33755 reaction equation
Br.[NH2:2][C:3]1[S:4][C:5]2[C:11]([C:12]([O:14][CH2:15][CH3:16])=[O:13])=[CH:10][CH:9]=[CH:8][C:6]=2[N:7]=1.Br.NC1SC2C=CC(C(OCC)=O)=CC=2N=1>>[NH2:2][C:3]1[S:4][C:5]2[C:11]([C:12]([O:14][CH2:15][CH3:16])=[O:13])=[CH:10][CH:9]=[CH:8][C:6]=2[N:7]=1

Participants

3

Reactant 2

HCID 86593371Ethyl 2-amino-1,3-benzothiazole-7-carboxylate hydrobromideHCID 86593372Ethyl 2-amino-1,3-benzothiazole-5-carboxylate hydrobromide

Product 1

HCID 45076983Ethyl 2-aminobenzo[d]thiazole-7-carboxylate

Procedure

A solution of thiocarbamate (1.95 g, 12.2 mmol, 2.11 eqiv) in chloroform (10 mL) was added dropwise over a period of 40 min to a vigorously maintained mixture of ethyl 3-[(aminocarbonothioyl)amino]benzoate (1.30 g, 5.78 mmol, 1.00 eqiv), 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 to provide 1.65 g (95%) of product 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 to provide pure ethyl 2-amino-1,3-benzothiazole-7-carboxylate. 1H NMR (500 MHz, DMSO-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).

Workup

  1. customThis product was partitioned between saturated aqueous solution of sodium bicarbonate (25 mL)
  2. additiona mixture of ethyl acetate (70 mL) and tetrahydrofuran (30 mL)
  3. customThe organic layer was separated
  4. dry with materialdried over anhydrous sodium sulfate
  5. concentrationconcentrated
  6. customThe residue was crystallized form ethyl acetate

Sources & evidence

ORD record
ord-81377f0ddffd4656b254212f2b9f9852
Source dataset
uspto-grants-2008_09
Patent number
US07429664B2

Reaction notes

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