反应详情

That is, first the known compound (XIV)(see European patent publication No. 286089) is reacted with 1,3-dichloroacetone in an organic solvent such as chloroform, methylene chloride or a lower alcohol to produce 3-chloro-2-oxopropyl N-(2,3,4-trifluorophenyl)dithiocarbamate (XV). The compound (XV) is then heated with an inorganic acid such as hydrochloric acid or sulfuric acid in a lower alcohol such as ethanol to give 4-chloromethyl-3-(2,3,4-trifluorophenyl)-2(3H)-1,3-thiazolethione (XVI). The compound (XVI) is then reacted with methylamine in an aprotic organic solvent such as N,N-dimethylformamide or acetonitrile to give 1H,4H-thiazolo[3,4-a]quinoxaline-1-thione derivative (XVII). The compound (XVII) is then reacted with a lower alkyl iodide in a polar solvent such as N,N-dimethylformamide, acetonitrile or ethanol to give a 1-(lower alkyl)thioquinoxalino[1,2-c]thiazolium iodide (XVIII). Then the compound (XVIII) is reacted with a di(lower alkyl) malonate sodium, which is prepared from di(lower alkyl) malonate and sodium hydride, in an organic solvent such as tetrahydrofuran or dioxane to give di(lower alkyl) (1H,4H-thiazolo[3,4-a]quinoxalin-1-ylidene)malonate (X).