Alchemists were perhaps the first practical chemists, but they did not have the advantage of knowing anything about atomic structure or nuclear reactions. No chemical reaction can produce gold from another element; a nuclear reaction is required. Even if they had envisioned a nuclear reaction that would produce gold from another isotope, they clearly did not have the means to accomplish this .The situation has indeed changed, and modern day chemists could design experiments to change lead into gold. The question now is why anyone would want to, as the cost would be prohibitive.