Hydrochloric Acid → Rivoglitazone

Participants

Reaction Steps

A mixture of 21.8 g of 5-methoxy-N-methyl-1,2-phenylenediamine (see Referential Example 9, Japanese Patent Application Publication No. Hei-9 (1997)-295970), 63.4 g of 5-(4-methoxycarbonylmethoxybenzyl)thiazolidin-2,4-dione (see Referential Example 21, Japanese Patent Application Publication No. Hei9-(1997)-295970), 250 ml of 1,4-dioxane and 750 ml of conc. hydrochloric acid was heated under reflux for 60 hours. The reaction mixture was cooled with ice, and the precipitate was filtered. The precipitate was mixed with 800 ml of 5% aqueous sodium hydrogencarbonate solution and stirred at room temperature for 2 hours. The insoluble material was filtered, dissolved in a mixture of 1000 ml of N,N-dimethylformamide and 200 ml of methanol and treated with activated charcoal. The activated charcoal was filtered off, and the filtrate was concentrated to about 50 ml by evaporating the solvents. To the residue was added 750 ml of diethyl ether and this was then allowed to stand at room temperature for 2 days. The precipitate was filtered to give 20.1 g of the desired compound having a melting point of 267-271° C. having an Rf=0.68 (thin layer chromatography on silica gel; 5% ethanol-methylene chloride solution).

Provenance & Evidence