[CH3:1][S:2][C:3]1[NH:4][C:5]([C:13]([O:15][CH2:16][CH3:17])=[O:14])=[C:6]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[N:7]=1.[N+](=[CH2:20])=[N-].C(O)(=O)C>CCOCC>[CH3:20][N:7]1[C:6]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[C:5]([C:13]([O:15][CH2:16][CH3:17])=[O:14])[N:4]=[C:3]1[S:2][CH3:1]Diethyl 2-(methylthio)imidazole-4,5-dicarboxylate (10 g; 0.039 tool) was slowly added in small portions to a solution of diazomethane in ether (containing approximately 3 g of diazomethane). Nitrogen was evolved immediately and the solution was allowed to stand at room temperature overnight. Excess diazomethane was then decomposed by the addition of dilute acetic acid and the reaction mixture was worked up in the usual way. Diethyl 1-methyl-2-(methylthio)imidazole-4,5-dicarboxylate (10.2 g; 97%) was obtained as a thick yellow oil.
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