Methyl pyruvate undergoes CH bond scission on Pt(111) at room temperature to trigger surface-mediated enol formation and subsequent self-assembly into enol superstructures. This process may be inhibited by performing the experiment below the temperature for CH bond scission or, at room temperature, by using a background pressure of H-2. Superstructure formation is not due to a polymerization reaction. Hence, it is unlikely that rate enhancement of the enantioselective hydrogenation of methyl pyruvate on cinchona-modified Pt catalysts is simply due to the absence of a substrate polymerization reaction under reaction conditions.