合成路线1

Eplerenone was prepared by several related ways. Microbiological hydroxylation of canrenone (I) provided the 11-a hydroxy derivative (II). This was converted to enamino compound (IV) by double addition of cyanide, followed by cyclization, on treatment with acetone cyanohydrin (III) in the presence of triethylamine and lithium chloride in DMF or, alternatively, by treatment with sodium cyanide and sulfuric acid. Hydrolysis of enamine (IV) with HCl in a methanol-water solution gave diketone (V), and further reaction with sodium methoxide in refluxing methanol gave hydroxyester (VI). After mesylation of the 11-a hydroxyl group with with mesyl chloride and triethylamine in cold dichloromethane, elimination of the resulting sulfonate (VII) to give olefin (VIII) was achieved on treatment with potassium formate in a mixture of formic acid and acetic anhydride at 100 C. Other conditions used for the elimination were potassium acetate in trifluoroacetic acid-trifluoroacetic anhydride, isopropenyl acetate and p-TsOH, or thermoelimination in DMSO at 80 C. Alternatively, hydroxyester (VI) was reacted with sulfuryl chloride at -70 C, and then treated with imidazole at room temperature to afford olefin (VIII). Finally, epoxidation was performed by reaction with hydrogen peroxide in the presence of trichloroacetamide or trichloroacetonitrile and PO4HK2 to give eplerenone.