Five-membered ring heterocyclics with two or more hetero-atoms

14 A A Five-membered ring heterocyclics with two or more hetero-atoms 

Among the five-membered ring heterocyclics with more than one hetero-atom, the derivatives of imidazole, oxazole, thiazole and 1,2,4-triazole are particularly important. 

Oxazole and thiazole have virtually no significance as unsubstituted compounds. Imidazole is obtained in around 75% yield by the reaction of glyoxal, formaldehyde and ammonia at about 70 °C. 

4-Triazole is produced in high yields from 4-amino-l,2,4-triazole by deamination or by condensation of hydrazine with formamide. 

Examples of imidazole derivatives used as plant protection agents are the fungicides prochloraz (Schering) and imazalil (Janssen-Pharmaceutica). 

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