反应 #998

反应方程式

4-methoxy-1H-indole

pyridine

trichloroacetyl chloride

→

4-methoxy-3-trichloroacetyl-1H-indole

溶剂

dichloromethane

dichloromethane

反应条件

后处理

1. 1
   浓缩the mixture was concentrated in vacuo
2. 2
   workup.WAITplaced in a freezer overnight
3. 3
   过滤The precipitate was filtered
4. 4
   洗涤rinsed well with methanol
5. 5
   其他dried

实验过程

To a solution of 4-methoxy-1H-indole (7.15 g, 49 mmol) and pyridine (19.7 mL, 243 mmol) in dichloromethane (50 mL) at 0° C. under nitrogen was added dropwise a solution of trichloroacetyl chloride (27.1 mL, 243 mmol) in dichloromethane (50 mL). After stirring at 0° C. for an additional 1.5 h, the mixture was concentrated in vacuo. The residue was taken up in the minimal volume of methanol necessary and placed in a freezer overnight. The precipitate was filtered, rinsed well with methanol, and dried to yield 4-methoxy-3-trichloroacetyl-1H-indole. To a stirring solution of sodium methoxide (3.5 mL of a 25 weight % solution in methanol) in methanol (200 mL) at ambient temperature was added 4-methoxy-3-trichloroacetyl-1H-indole (9.07 g, 31.0 mmol) in portions over 0.75 h. After stirring an additional 0.75 h, the mixture was cooled in an ice bath, diluted with ice water, acidified with concentrated hydrochloric acid, and the methanol removed in vacuo. The resulting heterogeneous mixture was cooled in an ice bath, the precipitate filtered, rinsed with water, and dried to afford methyl 4-methoxy-1H-indole-3carboxylic ester. A slurry of this ester (5.6 g 27 mmol) in 50% aqueous sodium hydroxide (50 mL) and methanol (50 mL) was stirred at ambient temperature for 19 h. The mixture was cooled in an ice bath, acidified with concentrated hydrochloric acid, the precipitate filtered, rinsed with ice water, and dried to afford 4-methoxy-1H-indole-3-carboxylic acid.

来源