[CH2:1]([N:8]1[C:12]([CH3:13])=[C:11]([CH:14]2[S:19][CH:18](C(OCC)=O)[C:17](=[O:25])[CH2:16][S:15]2)[N:10]=[CH:9]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.S(=O)(=O)(O)O>O.Cl>[CH2:1]([N:8]1[C:12]([CH3:13])=[C:11]([CH:14]2[S:19][CH2:18][C:17](=[O:25])[CH2:16][S:15]2)[N:10]=[CH:9]1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1A mixture of 2-(1-benzyl-5-methyl-4-imidazolyl)-4-carbethoxy-1,3-dithian-5-one (15.5 g., 0.041 mole) in water (40 ml.) containing concentrated sulfuric acid (3.0 ml.) is heated at 100° C. for 4-5 hours. The mixture is cooled, diluted with 10% hydrochloric acid, washed with diethyl ether and filtered through a charcoal pad. The filtrate is made basic with sodium carbonate solution and extracted into methylene chloride. The solvent is dried and evaporated to give a dark brown oil (11.2 g.), 2-(1-benzyl-5-methyl-4-imidazolyl)-1,3-dithian-5-one, which is used as is in subsequent steps.
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