Synthesis of 14C‐labelled 2‐aminothiazole, 2‐amino‐5‐nitrothiazole, 2‐chloro‐5 nitrothiazole, and 1‐(5‐nitro‐2‐thiazolyl)‐2‐imidazolidinone (active substance of ambilhar®)

Abstract

A description is given of the preparation of 1‐(5‐nitro‐2‐thiazolyl)‐2‐imidazolidinone (active substance of the antiparasitic drug AMBILHAR®) in labelled form. By introducing ¹⁴C into the molecule, at position 4 of the imidazolidinone ring in one case and at position 2 of the thiazole ring in the other case, two differently labelled preparations were produced. The specific aetivities were 2.5 mCi/mmole and 0.33 mCi/mmole respectively. As intermediate products and by‐products of the syntheses, three further derivatives of ¹⁴C‐thiazole which have not hitherto been described were obtained, i.e. 2‐aminothiazole‐2‐¹⁴C, 2‐amino‐5‐nitrothiazole‐2‐¹⁴C, and 2‐chloro‐5‐nitrothiazole‐2‐¹⁴C.