Antiprotozoal Thiazoles. 2-(5-Nitro-2-thienyl)thiazoles

A series of 2-(5-nitro-2-thienyl)thiazoles and their vinylogs having substituted methylamine side chains has been prepared by halogen displacement on the corresponding 4-chloromethylthiazole. Of these, 4-morpholinomethyl-2-(5-nitro-2-thienyl)thiazole showed moderate activity against Trypanosoma cruzi and Trypanosoma rhodesiense in mice. This compound formed the lead for a series of analogous thiazole-4-carboxaldehyde hydrazones. Some of the latter were found active in curing murine Tryp. cruzi and Tryp. rhodesiense infections and to have low acute toxicity. A comparison with known active compounds is given and some structural features necessary for activity are discussed.