[Cl:1][C:2]1[C:15]([Cl:16])=[CH:14][C:5]2[N:6]([CH2:10][CH2:11][CH2:12][OH:13])[C:7](=[O:9])[NH:8][C:4]=2[CH:3]=1.C(N(CC)CC)C.[CH3:24][S:25](Cl)(=[O:27])=[O:26]>ClCCl>[CH3:24][S:25]([OH:27])(=[O:9])=[O:26].[Cl:1][C:2]1[C:15]([Cl:16])=[CH:14][C:5]2[N:6]([CH2:10][CH2:11][CH2:12][OH:13])[C:7](=[O:9])[NH:8][C:4]=2[CH:3]=1To a stirred mixture of 13.3 parts of 5,6-dichloro-1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one, 8 parts of N,N-diethylethanamine and 260 parts of dichloromethane are added dropwise 7.4 parts of methanesulfonyl chloride. Upon completion, stirring is continued for one hour at reflux temperature. The reaction mixture is washed with water, dried, filtered and evaporated. The solid residue is shaken with acidified water and 4-methyl-2-pentanone. The whole is filtered (the filtrate is set aside) and the filter-cake is dried, yielding a first fraction of 6.2 parts of 5,6-dichloro-1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one methanesulfonate. The 4-methyl-2-pentanone-phase is separated from the filtrate, dried, filtered and evaporated, yielding a second fraction of 8 parts of 5,6-dichloro-1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one methanesulfonate as an oily residue.
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