2-Chlorothiophene → 4-(5-Chlorothiophen-2-yl)-4-oxobutanoic acid

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Reaction Steps

As described for Example 1, 0.3 mole of 2-chlorothiophene is reacted with succinic anhydride to give 4-(5-chloro-2-thienyl)-4-ketobutyric acid (74%), m.p. 121°-123° C. The preceding compound is coupled to L-proline to give 1-[3-(5-chloro-2-thenoyl)propionyl]-L-proline (94%) as crystals, m.p. 131°-133° C. The above compound is reacted with bromine in acetic acid to give 1-[3-bromo-3-(5-chloro-2-thenoyl)-propionyl]-L-proline as a glass. As for Example 1, reaction of the preceding compound with sodium thioacetate in ethanol gives the desired product (84%) as a glass.

Provenance & Evidence