Ethanol → 2-Methyl-4-(6-carboxyhexyl)-thiazole-5-carboxylic acid

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Reaction Steps

The solution of 8 g of crude 2-methyl-4-(6-carbomethoxyhexyl)-thiazole-5-carboxylic acid methylester (VIII, R1 = CH3) in 25 ml of ethanol was treated with 40 ml of 2 N sodium hydroxide solution. The reaction mixture was refluxed for 30 minutes, then acidified with 5 N sulphuric acid under ice-cooling. After extracting the aqueous reaction mixture with 3 × 75 ml of ethyl acetate, the extract was dried over sodium sulphate and evaporated in vacuo. The obtained crude product was recrystallized from a mixture of acetone and n-hexane, affording 5.3 g of 2-methyl-4-(6-carboxyhexyl)-thiazole-5-carboxylic acid (IX, R1 = CH3). M.p.: 147-149° C.

Provenance & Evidence