IMPROVED PROCESS FOR THE PREPARATION OF THIAZOLIDINE-2,4-DIONE DERIVATIVES

An improved process for the preparation of 5-[4-[[3-Methyl-4-oxo-3,4-dihydroquinazolin-2-yl]methoxy]benzyl]thiazolidine-2,4-dione of formula (1) which comprises: reducing the compound of formula (2') where R represents a (C1-C4)alkyl group using Raney Nickel or Magnesium in alcohol having 1 to 4 carbon atoms or mixtures thereof, if desired reesterifying using sufphuric acid at a temperature in the range of 0° C. to 60° C. to obtain a compound of formula (3') wherein R is as defined above, hydrolyzing the compound of formula (3') wherein R is as defined above, by conventional methods to obtain the acid of formula (4), condensing the acid of formula (4) with N-methyl anthranilamide directly without any preactivation of the acid to produce the compound of formula (1) and if desired, converting the compound of formula (1) to pharmaceutically acceptable salts thereof by conventional methods.