Pr. Kumar et al., Synthesis of tenidap: An improved process for the preparation of 5-chloro-2-oxindole-1-carboxamide, ORG PROC R, 5(1), 2001, pp. 61-64
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.