p-Toluenesulfonic acid → 1-Isopropylsulfonyl-2-amino-6-(alpha-aminocarbonylmethylenebenzyl)benzimidazole

Participants

Reaction Steps

A solution of 3.0 g. of p-toluenesulfonic acid and 3.0 g. of 1-isopropylsulfonyl-2-amino-6-(α-hydroxy-α-aminocarbonylmethylbenzyl)benzimidazole (prepared as described in Example 23) in 100 ml. of chloroform was heated at reflux for four hours. The reaction mixture then was cooled, washed with aqueous sodium bicarbonate solution and with water, dried, and the solvent was removed by evaporation under reduced pressure. Crystallization of the product thus formed from tetrahydrofuran afforded 1.1 g. of trans-1-isopropylsulfonyl-2-amino-6-(α-aminocarbonylmethylenebenzyl)benzimidazole, M.P. 218°-219° C. Yield 35%, and 1.0 g. of the corresponding cis-isomer, M.P. 211°-212° C., yield 32%.

Provenance & Evidence