20886
Here , the main pathways were N - oxidation of the pyridine and / or pyrimidine ring and a ring contraction of the pyrimidine ring into an imidazole ring .
 Chemical: N; Chemical: pyridine; Chemical: pyrimidine; Chemical: pyrimidine; Chemical: imidazole
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: N; Chemical: pyridine; Chemical: pyrimidine; Chemical: pyrimidine; Chemical: imidazole