15.5 g of 5-[4-(6-hydroxy-2,5,7,8-tetramethyl chroman-2-yl-methoxy) benzyl]-2-iminothiazolidine-4-one, prepared by the process as described in Example-1, was added to a mixture of 225 ml of acetic acid, 75 ml of conc. hydrochloric acid and 40 ml of water and the mixture was refluxed for 12 hrs. The reaction mixture was cooled to room temperature and 66.2 g of sodium bicarbonate was added and once the evolution of carbondioxide had ceased, the solvent was distilled off applying high vacuum. A 10:1 by volume mixture of benzene and ethyl acetate was added to the residue and the crude product was washed with a mixture of equal volumes of a saturated aq. sodium bicarbonate solution & water. The organic layer was dried over anhydrous sodium sulphate and the solvent was distilled off. The resulting crude product was quickly eluted tom a silica gel column with 50% ethylacetate-hexane to furnish 12.5 g of the required 5-{4-(6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-yl-methoxy) benzyl) thiazolidine-2,4-dione (Troglitazone) with a HPLC purity of ~67-70%.
