43142-64-9

Ethyl 7-chloroindole-2-carboxylate is an organic synthesis intermediate, mainly used in the synthesis of drugs and pesticide molecules containing indole rings, and is also an important component in chemical research.

General procedure for the synthesis of ethyl 7-chloro-1H-indole-2-carboxylate from the compound (CAS:115050-49-2): 500 g of polyphosphoric acid and 250 g of phosphoric acid were mixed, stirred and heated up to 90°C. Under stirring conditions, 65 g of phenylhydrazine 2-chlorophenylpyruvate pyruvic acid was slowly added and the temperature of the reaction was controlled to be between 90°C and 100°C. The reaction took about 1 hour. The dosing process takes about 1 hour. After completion of dosing, the reaction temperature was maintained to continue the reaction for 20 minutes and the reaction progress was monitored by TLC. Upon completion of the reaction, 1500 g of ice-water mixture was slowly added to quench the reaction and cooled to room temperature. The precipitate was collected by filtration, washed with water and dried to give a light yellow solid product. Upon drying, 51.3 g of ethyl 7-chloro-1H-indole-2-carboxylate was obtained in 85% yield.

[1] Patent: CN104402795, 2017, B. Location in patent: Paragraph 0060; 0062