ChemicalBook CAS DataBase List 6-Benzothiazolecarboxylicacid,methylester(9CI)

6-Benzothiazolecarboxylicacid,methylester(9CI) synthesis

8synthesis methods

Product Name:6-Benzothiazolecarboxylicacid,methylester(9CI)
CAS Number:73931-63-2
Molecular formula:C9H7NO2S
Molecular Weight:193.22

3622-35-3 Synthesis

3622-35-3
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18107-18-1
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6-Benzothiazolecarboxylicacid,methylester(9CI)

73931-63-2
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Yield: 82%

Reaction Conditions:

Stage #1:benzothiazole-6-carboxylic acid;diazomethyl-trimethyl-silane in methanol;dichloromethane at 0 - 20;
Stage #2: with acetic acid in methanol;dichloromethane for 0.5 h;

Steps:

23.1
Benzothiazole-6-carboxylic acid (71a, 5.0 g, 27.93 mmol) was dissolved in DCM (96 mL) and MeOH (32 mL) and cooled to 0° C. A solution of trimethylsilyl-diazomethane (28 mL, 2.0M in hexane) was added dropwise and the resulting solution was gradually warmed to RT and stirred overnight. The reaction was quenched slowly by careful addition of HOAc (2 mL) and stirred for 30 min. The solution was concentrated, diluted with EtOAc and washed with saturated NaHCO₃solution. The organic extracts were dried (Na₂SO₄), filtered and concentrated in vacuo. The crude residue was purified by SiO₂chromatographed eluting with 15% EtOAc/hexane to afford 4.44 g (82%) of 71b as a white solid: ¹H NMR (300 MHz, CDCl₃): 9.15 (s, 1H), 8.68 (m, 1H), 8.16 (m, 2H), 3.97 (s, 3H).

References:

Roche Palo Alto LLC US2006/40927, 2006, A1 Location in patent:Page/Page column 38