[SH:1][CH2:2][C:3]([O:5]CC)=O.[CH3:8]OCCOC.C([Li])CCC.[CH2:19]([N:26]1[C:30]([CH3:31])=[C:29]([CH:32]=[CH:33][C:34](OCC)=O)[N:28]=[CH:27]1)[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1>CCCCCC>[CH2:33]([C:32]1([C:29]2[N:28]=[CH:27][N:26]([CH2:19][C:20]3[CH:21]=[CH:22][CH:23]=[CH:24][CH:25]=3)[C:30]=2[CH3:31])[CH2:8][C:3](=[O:5])[CH2:2][S:1]1)[CH3:34]A solution of ethyl mercaptoacetate (7.45 g., 0.062 mole) in 59 ml. of dry 1,2-dimethoxyethane is cooled to 5° C. and n-butyl lithium (41.3 ml., 0.062 mole) in hexane is added dropwise over 1/2 hour under a nitrogen atmosphere. To this solution is added ethyl 3-(1-benzyl-5-methyl-4-imidazolyl)-2-propenoate (13.0 g., 0.0514 mole) in 50 ml. of 1,2-dimethoxyethane at 10° C. The mixture is stirred at 50°-55° C. for 6 hours and is left at room temperature overnight. The reaction mixture is cooled in ice and is diluted with 300 ml. of ether and filtered. The solid is dissolved in 100 ml. of water and is acidified with dilute hydrochloric acid. The mixture is made basic with sodium bicarbonate and is extracted with a mixture of chloroform and methylene chloride. The combined extracts are dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The product ethyl 2-[1-benzyl-5-methyl-4-imidazolyl]-4-oxotetrahydrothiophene-5-(and/or 3)-carboxylate is obtained as a brown viscous liquid (12.6 g.).
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