Patent ID: 6900335

Claim:
A process for preparing 5-fluorooxindole represented by the formula (3): which comprises (A) cyclizing 2-(5-fluoro-2-nitrophenyl)malonic acid diester represented by the formula (1): wherein R 1 and R 2 are the same or different from each other and each represents a group which does not participate in the reaction, and wherein R 1 and R 2 each represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an aralkyl group having 7 to 10 carbon atoms or an aryl group having 6 to 14 carbon atoms, under reductive conditions to form a 5-fluorooxindole-3-carboxylic acid ester represented by the formula (2): wherein R 1 has the same meaning as defined above, in a first step, and (B) then, decarboxylating the 5-fluorooxindole-3-carboxylic acid ester in a second step.