m-Chloroperbenzoic acid → 2-(2-aminobenzylsulfinyl)-4,5,6,7-tetrahydro-1H-benzimidazole

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Reaction Steps

To a solution of 1.3 g (5.0 mmol) of 2-(2-aminobenzylthio)-4,5,6,7-tetrahydro-1H-benzimidazole in 13 ml of chloroform was added under stirring and chilling with ice (5°-10° C.) 1.08 g (5.0 mmol) of 80% m-chloroperbenzoic acid for approx. 15 min. The mixture was further stirred for 15 min., and to the mixture was added saturated aqueous sodium hydrogencarbonate solution. Thus precipitated solid was collected by filtration and washed with two portions of water and one portion of acetonitrile. There was obtained 590 mg of a crude product. The chloroform portion of the mother liquor was taken out and subjected to extraction using 10 ml of 0.2N aqueous NaOH. The aqueous alkaline solution was made ammonia alkaline by addition of 20% aqueous NH4Cl to precipitate a crystalline product. The crystalline product was collected and washed successively with two portions of water and one portion of acetonitrile to give 130 mg of a crude product. The crude products were combined and dissolved in 30 ml of 0.5N aqueous NaOH. The aqueous solution was washed with three portions of chloroform and then made ammonia-alkaline by addition of 20% aqueous NH4Cl to precipitate a crystalline product. The obtained product was washed successively with two portions of water, one portion of acetonitrile and one portion of diethyl ether and then dried under reduced pressure at 35° C. for 8 hrs. to 624 mg of the desired compound as a white crystalline product, yield 45.4%.

Provenance & Evidence