Studies On Biological Activities And Synthesis Of Heterocycle Unsymmetric Ureas

Unsymmetrical ureas are very useful fine chemicals. They are widely used as herbicides, pesticides, plant growth regulators and medicinal intermediates.However, the synthetic protocols of ureas generally utilize phosgene or phosgene-based isocyanates as starting materials, both of which are toxic or unstable. Therefore, it is necessary to develop some phosgene-free routes for unsymmetrical ureas. The experimental results showed that these reactions proceeded efficiently under reaction conditions studied. The all microwave irradiation reactions can be completed within a few minutes in a satisfactory yield. In contrast, the same reactions required several hours in lower yield by traditional heating method. The main advantages of microwave method are rapid reaction rate, high yield, less by-products, and convenient manipulation.Twenty four benzothiazole ureas ( I ) were synthesized from heterocyclic amino compounds and phenyl 4-chlorobenzo[d]thiazol-2-ylcarbamate; fifty 1, 3, 4-thiadiazole urea derivatives (II, III) were synthesized from heterocyclic amino compounds phenyl-5-(pyridine-3-y1)-l, 3,4-thiadiazol-2-ylcarbamate orphenyl-5-(trifiuoro-methyl)-1, 3, 4-thiadiazol-2-ylcarbamate.twenty two pyridylthiourea derivatives (IV) were synthesized from heterocyclic amino and phenyl thiazolo[5, 4-b]pyridin-2-ylcarbamate. The structures of the compounds were characterized by elemental analyses, 1H NMR and ESI-MS. The structural formulas of the title compounds are as follows respectively: Preliminary bioassay shows that some thiazoles display moderate plant growth regulatory activities; some 1, 3, 4-thiadiazole urea derivatives display moderate fungicidal activities; some pyridylthiourea derivatives show moderate antifungal and good plant growth regulatory activities, In additional, the structure-activity relationships of the target compounds were discussed.