AN IMPROVED PROCESS FOR PREPARING 2-OXINDOLES OF FORMULA I, A KEY RAW MATERIAL FOR MAKING PHARMACEUTICAL DRUGS AND INTERMEDIATES THEREOF

摘要

The present invention provides an improved processes having practical utility for preparing 2-oxindoles of formula I comprising preparation of 2-nitroarylmalonate diester of formula II as first intermediate and subsequent insitu reductive cyclisation using metal acid combination and its modified work-up to form compound of formula I free from metal generated impurity of formula M(OH)X wherein M is metal cation and X is anion. R is selected from hydrogen, linear, branched or cyclic alkyl, aryl, substituted aryl, heteroaryl, haloalkyl like CF₃, alkoxy, haloalkoxy, thioalkyl and halogen preferably chloro Formula I wherein R' and R" are same or different and is selected from linear.branched and cyclic alkyl (C₁C₄groups)preferably methyl R is selected from hydrogen, linear, branched or cyclic alkyl, aryl, substituted aryl, heteroaryl, haloalkyl like CF₃, alkoxy, haloalkoxy, thioalkyl and halogen preferably chloro Formula II.