P(Cl)(Cl)(Cl)(Cl)Cl.[CH3:7][C:8]1[N:9]2[CH:15]=[C:14]([C:16]([OH:18])=[O:17])[N:13]=[C:10]2[S:11][CH:12]=1.[CH2:19](O)[CH3:20]>C(Cl)Cl.O>[CH3:7][C:8]1[N:9]2[CH:15]=[C:14]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[N:13]=[C:10]2[S:11][CH:12]=1To a solution of 6.3 g of phosphorus pentachloride in 120 ml of dry methylene chloride, 5 g of 3-methyl-imidazo-(2,1-b)thiazole-6-carboxylic acid (prepared as described in Example 10) is added and the suspension obtained is refluxed for 3 hours. After vacuum evaporation of the solvent the residue obtained being 3-methyl-imidazo-(2,1-b)thiazole-6-carboxylchloride chlorohydrate is dissolved in 100 ml of abs. ethanol and the solution is refluxed for 4 hours. The solvent is removed and the residue obtained is dissolved in water. The solution obtained is neutralised to pH 7.5 to yield 5 g of 3-methyl-6-carboethoxy-imidazo-(2,1-b)thiazole; m.p. 117°-119°.
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