[Cl:1][C:2]1[NH:3][C:4]2[CH:10]=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=1.[H-].[Na+].[CH2:13](Br)[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.O>CN(C)C=O>[CH2:13]([N:3]1[C:4]2[CH:10]=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=[C:2]1[Cl:1])[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1A solution of 2-chlorobenzimidazole (100 g, 0.65 mol) in 500 ml of dimethylformamide (DMF) was added dropwise to a stirred suspension of 60% sodium hydride-mineral oil dispersion (28 g, 0.70 mol) in 500 ml of DMF. Mild intermittent cooling was required. After the addition was completed the mixture was stirred an additional 15 min and benzylbromide (82.6 g, 0.49 mol) was added dropwise with mild intermittent cooling. The reaction mixture was stirred an additional 1.5 h and 1 L of water was added. The mixture was extracted with benzene. The extract was dried (Na2SO4), concentrated and the residue crystallized from isopropyl ether to obtain 110 g (93%), mp 102°-105° C.
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