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To a flask fitted with a condenser, stirrer and thermometer were added 20 g. of the dioxalate salt of 2-dimethylaminomethyl-4-(2-aminoethyl)thiomethylthiazole, and 50 ml. of water. The pH of the solution was adjusted to 6.1 by the addition of 52 ml. of 2N aqueous potassium hydroxide, and 7.5 g. of methylcarbonimidodithioic acid, dimethyl ester, was added. The mixture was stirred at 75° for 3 hours, and was then cooled to ambient temperature. Its pH was adjusted to 6.5 by addition of 3.2 ml. of 2N aqueous potassium hydroxide, and 100 ml. of dichloromethane was added with vigorous mixing. The pH was adjusted to 6.5 again with 1 ml. of 2N aqueous potassium hydroxide, and the organic layer was separated and discarded. The aqueous layer was mixed with 100 ml. of additional dichloromethane, and its pH was adjusted to 13 by addition of 55 ml. of 2N aqueous potassium hydroxide. The organic layer was separated, dried over potassium carbonate and evaporated under vacuum to obtain 13.1 g. of product, which was found by NMR analysis to be substantially identical to that of Example 1. Its purity was 94.6% by high performance liquid chromatographic analysis.

1. customTo a flask fitted with a condenser, stirrer
2. additionthermometer were added 20 g
3. additionThe pH of the solution was adjusted to 6.1 by the addition of 52 ml
4. additionIts pH was adjusted to 6.5 by addition of 3.2 ml
5. customof 2N aqueous potassium hydroxide, and the organic layer was separated
6. additionThe aqueous layer was mixed with 100 ml
7. additionof additional dichloromethane, and its pH was adjusted to 13 by addition of 55 ml
8. customThe organic layer was separated
9. dry with materialdried over potassium carbonate
10. customevaporated under vacuum
11. customto obtain 13.1 g