Omeprazole imidazole ring

Omeprazole 5 -Methoxy-2- [(4 -methoxy-3,5-dimethyl-2-pyridinyl) methyl] sulfinylj -17/-benzimidazol O-methylation, imidazole ring formation using thiourea, A-oxidation, nucleophilic displacement, A-methylation, S -oxidation... 

It is also of interest that a 6-methyl group in the pyridine ring of omeprazole produces an acid-stable (and therefore inactive) analog. Molecular models indicate that such 6-substituents sterically interfere with the imidazole ring. The interpretation is that this will ster-ically prevent the formation of the spiro intermediate (Fig. 13-4), thus supporting the proposed mechanism for omeprazole. 

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