Reaction #337431

Reaction equation

3-cyclopropylamino-but-2-enoic acid ethyl ester

p-benzoquinone

→

title compound

Yield 21.0%

1-Cyclopropyl-5-hydroxy-2-methyl-1H-indole-3-carboxylic acid ethyl ester

Yield 21.0%

Solvents

acetic acid

Conditions

Workup

1. 1
   Othera dark solid is precipitated
2. 2
   WashThe solid is washed with acetic acid and water
3. 3
   Otherdried
4. 4
   Otherpurified via flash chromatography
5. 5
   Washeluting with dichloromethane
6. 6
   OtherThe product is triturated in dichloromethane-hexane

Procedure

Neat 3-cyclopropylamino-but-2-enoic acid ethyl ester (5.63 g, 33.2 mmol) is added to a mixture of p-benzoquinone (7.19 g, 66.5 mmol) and acetic acid (120 mL). The mixture is stirred at room temperature for 5 h and a dark solid is precipitated. The solid is washed with acetic acid and water, dried, adsorbed onto silica gel, and purified via flash chromatography eluting with dichloromethane. The product is triturated in dichloromethane-hexane to afford the title compound (440 mg, 21%). ES/MS m/e 260.0 (M+1)

Source