Synthesis of tenidap: An improved process for the preparation of 5-chloro-2-oxindole-1-carboxamide

An industrially viable, robust, and economic process is developed for Tenid ap sodium and its important intermediate 5-chloro-2-oxindole-1-carboxamide. Use of inorganic cyanates, in place of organic isocyanates, makes the proc ess simple and commercially viable. The advantage of using acetic anhydride and sodium acetate over reported reagents such as trifluoroacetic acid and its anhydride on industrial scale is described. Drastic reduction of DMAP in the final step and overall improvement of yields makes the process econo mical.