86% |
With triethylamine In methanol Reflux; |
|
85% |
With triethylamine In dichloromethane at 20℃; for 2h; |
|
80% |
With potassium carbonate In acetone for 40h; Heating; |
|
79% |
With potassium carbonate In acetone for 16h; Heating; |
|
76% |
With potassium carbonate In acetone for 0.0583333h; microwave irradiation; |
|
76% |
With aluminum oxide for 0.0666667h; Microwave irradiation; |
|
75.1% |
With triethylamine In ethanol for 3h; Reflux; |
Methyl 2-(benzo[d]thiazol-2-ylthio)acetate (4)
To a solution of 3.34 g 1,3-benzothiazol-2-ylthiol 3(20.00 mmol), triethylamine (25.00 mmol) in EtOH was added 5 cm3 ethyl chloroacetate (25.00 mmol). The reaction mixture was refluxed in 20 cm3 EtOH for 3 h. After removal of EtOH under reduced pressure, the resulting mixture was recrystallized with EtOH to obtain white crystals (3.80 g, 75.10%). The spectra of acetate 4 were similar to the Ref. [39]. |
72% |
Stage #1: 2-Mercaptobenzothiazole With potassium <i>tert</i>-butylate In tetrahydrofuran for 0.5h; Reflux;
Stage #2: chloroacetic acid ethyl ester In tetrahydrofuran for 5h; Reflux; |
|
72% |
With potassium carbonate In acetone Reflux; |
3.1.2. Synthesis of Ethyl 2-(Benzazol-2-yl-thio)acetates 2a,2b
General procedure: The corresponding benzazol-2-thiol (0.015 mol), ethyl 2-chloroacetate, (0.015 mol, 1.61 mL),and K2CO3 (0.015 mol, 2.07 g) were refluxed in acetone (70 mL) for 8-10 h. After completion of thereaction, the solvent was removed using reduced pressure. The precipitated product was washed withwater, dried and recrystallized from EtOH. The following compounds were preapared in this way:ethyl 2-(benzimidazole-2-ylthio)acetate (2a), CAS No:5429-62-9, Yield 65%, m.p. = 99-101 °C (measured),m.p. = 97 °C (reported) [61]; ethyl 2-(benzothiazol-2-ylthio)acetate (2b), CAS No:24044-88-0, Yield 72%,m.p. = 45-47 °C (measured), m.p. = 42-44 °C (reported) [62].3.1.3. Synthesis of 2-((5-Substitutedbenzazol-2-yl)thio)acetohydrazides |
69% |
With potassium carbonate In acetone for 8h; Reflux; |
Ethyl 2-(benzothiazol-2-ylthio)acetate 1
A mixture of benzothiazole-2-thiol (5.51 g, 33 mmol) and ethyl2-chloroacetate (4.24 ml, 39 mmol) were refluxed in acetone(100 mL) in the presence of potassium carbonate (4.55 g, 33mmol) for 8 h. After completion of the reaction, acetone wasremoved under reduced pressure, the residue was washed withwater, dried, and recrystallized from EtOH. Yield 69%, M.P. =58-59°C (measured), M.P. = 58°C (reported.[41]) |
53.7% |
With potassium carbonate In acetone for 1h; Heating; |
|
|
With potassium carbonate In acetone for 20h; Heating; |
|
|
With potassium carbonate In acetone |
|
|
With potassium carbonate In acetone at 20℃; for 3h; |
4.2.2. Ethyl 2-(2-benzothiazolylsulfinyl)acetate [(+/-)-2]
To a stirred suspension of 2-mercaptobenzothiazole (3.34 g, 20 mmol) and potassium carbonate (5.53 g, 40 mmol) in acetone (30 mL) was added ethyl chloroacetate (2.43 mL, 20 mmol). After being stirred for 3 h at rt, the reaction mixture was filtrated to remove precipitates and the filtrate was concentrated in vacuo. The residue was diluted with ethyl acetate (100 mL) and washed with water (30 mL) and brine (20 mL). The organic phase was dried over sodium sulfate, filtrated, and concentrated in vacuo to give ethyl 2-(2-bezothiazolylthio)acetate as a yellow oil (7.46 g, >99%). This crude acetate (7.46 g, 29.5 mmol) was dissolved in dichloromethane (40 mL) and then the solution was cooled to 0 °C. A solution of m-chloroperbenzoic acid (4.59 g, 26.6 mmol) in dichloromethane (80 mL) was slowly added into the solution at 0 °C. The mixture was stirred for 3 h at rt and then quenched with saturated aqueous Na2S2O3 (10 mL). The organic phase was washed with saturated aqueous NaHCO3 (10×2 mL) and brine (10 mL), dried over sodium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography (hexane/EtOAc=6:1-1:1) to afford ethyl 2-(2-benzothiazolylsulfinyl)acetate (2, 5.16 g, 96%); pale yellow crystal; mp 60 °C; IR (neat) 2994, 2361, 1732, 1559, 1479, 1429, 1267, 1063, 999, 903, 762, 733 cm-1; 1H NMR (400 MHz, CDCl3) δ 1.26 (t, J=6.8 Hz, 3H), 4.12 (d, J=14.4 Hz, 1H), 4.23 (d, J=14.4 Hz, 1H), 4.25 (q, J=6.8 Hz, 2H), 7.52 (t, J=8.0 Hz, 1H), 7.59 (t, J=8.0 Hz, 1H), 8.02 (d, J=8.0, Hz, 1H), 8.08 (d, J=8.0 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 14.0, 60.5, 62.5, 122.2, 124.0, 126.4, 127.0, 136.0, 153.5, 163.8, 175.7; HRMS (FAB) m/z for C11H12O3NS2 [M+H]+ calcd 270.0259, found 270.0263. |
|
With potassium carbonate In acetone |
|
|
With trimethylamine In methanol |
|
|
With potassium carbonate In acetone for 24h; Reflux; |
|
|
With potassium carbonate In acetone for 24h; Reflux; |
|