Thiophen Fused to Various Five-Membered Rings

Thiophen Fused to Various Five-Membered Rings. - The reaction of ethyl 

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Imidazole is a heterocyclic five-membered ring containing nitrogen atoms. Various imidazole derivatives are found to possess biological activities. Biotin is of interest here, it is a heterocychc sulfur-containing B-complex vitamin with imidazole and thiophene rings fused along the C - C bond. Biotin serves as a carrier of CO2 in carboxylation reactions. Biotin-enzyme reacts with CO2 in the presence of ATP to form a carboxybiotin-enzyme complex. This complex hands over the CO2 to pyruvate to produce oxaloacetate [139]. 

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