Complex sentence: The same year, the ayuntamiento of Mexico City, supported by viceroy José de Iturrigaray, claimed sovereignty in the absence of the legitimate king, the reaction led to a coup against the viceroy and led the leaders of the movement to jail.
Split into simpler sentences: The same year, the ayuntamiento of Mexico City, supported by viceroy José de Iturrigaray, claimed sovereignty in the absence of the legitimate king. That led to a coup against the viceroy and led the leaders of the movement to jail.