348-36-7

light yellow powder

Reactant for preparation of antitumor agents 1 Reactant for preparation of antihyperlipidemic agents 2 Reactant for preparation of factor Xa inhibitors 3 Reactant for preparation of potential antiarrhythmic agents 4 Reactant for preparation of inhibitors of the cytosolic phospholipase A2 5 Reactant for preparation of thromboxane receptor antagonist and thromboxane synthase inhibitor via Mitsunobu reaction 6

Phenylhydrazone 4-fluorophenylhydrazine pyruvate (65 g) was used as a raw material, which was added to a mixture of polyphosphoric acid (500 g) and phosphoric acid (250 g) that had been pre-mixed and heated to 75°C. The reaction was carried out by stirring for 1 hour. The reaction was stirred at a temperature range of 75-85°C for 1 hour to ensure complete reaction of the feedstock. Subsequently, the reaction was continued at the same temperature conditions for 20 minutes and the completion of the reaction was confirmed by monitoring. The reaction mixture was slowly poured into an ice-water mixture (1500 g) and cooled to room temperature. The resulting light yellow solid was separated and dried to give the final ethyl 5-fluoroindole-2-carboxylate (52.2 g) in 87% yield.

[1] Patent: CN104402795, 2017, B. Location in patent: Paragraph 0040; 0042
[2] Hoppe-Seyler's Zeitschrift fuer Physiologische Chemie, 1954, vol. 297, p. 229,233
[3] Journal of the Chemical Society, 1955, p. 1283,1284
[4] Archiv der Pharmazie, 2008, vol. 341, # 5, p. 294 - 300
[5] European Journal of Medicinal Chemistry, 2013, vol. 69, p. 125 - 138