تفاعل #2045095

معادلة التفاعل

phosphorous oxychloride

oxazole-2-thiol

5-(4-chlorophenyl)oxazole-2-thiol

triethyl amine

water

→

2-chloro-5-(4-chlorophenyl)oxazole

المردود 13.0%

ظروف التفاعل

المعالجة

1. 1
   استخلاصextracted with ethyl acetate (3×40 mL)
2. 2
   غسيلThe combined organic layers were washed with aq. sat. bicarbonate (100 mL) and water (50 mL)
3. 3
   أخرىDrying
4. 4
   تركيز(sodium sulfate) and concentration in vacuo
5. 5
   أخرىyielded crude product (615 mg), which
6. 6
   أخرىwas purified by column chromatography (SiO2, 5-40% ethyl acetate in heptanes)

الإجراء التجريبي

2-amino-1-(4-chlorophenyl)ethanone hydrochloride (0.80 g, 3.88 mmol) and carbon disulfide (0.47 mL, 0.59 g, 7.76 mmol) was suspended in ethanol (10 mL). To this was slowly added a solution of sodium carbonate (0.44 g, 4.08 mmol) in water (4 mL) at ambient temperature. After heating to 80° C. ext. temp. for 18 h the cold mixture was filtered. The filtrate was diluted with acetic acid (40 mL) and stirred for 15 min. at room temperature. Evaporation of the solvents in vacuo gave 1.42 g of a crude 5-(4-chlorophenyl)oxazole-2-thiol which was of ca. 61% purity (HPLC-MS) and used as is in the next step. The crude oxazole-2-thiol compound (1.42 g, max. 3.88 mmol) was suspended in phosphorous oxychloride (5 mL). To this was added dropwise triethyl amine (1.15 mL, 0.84 mg, 8.27 mmol) and the mixture heated to 105° C. ext. temperature for 4 h. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (3×40 mL). The combined organic layers were washed with aq. sat. bicarbonate (100 mL) and water (50 mL). Drying (sodium sulfate) and concentration in vacuo yielded crude product (615 mg), which was purified by column chromatography (SiO2, 5-40% ethyl acetate in heptanes) to give pure 2-chloro-5-(4-chlorophenyl)oxazole (105 mg, 0.49 mmol, 13%, purity 96% HPLC-MS).

المصدر