I assume you are referring to the drug accidentally ingested by the main protagonist (Scarlett Johansson) in Luc Besson's movie Lucy. The drug was shown to increase her brain usage to 100%.
CPH4 is actually real and its chemical name is 6-carboxy-5,6,7,8-tetrahydropterin. It is formed by an enzyme catalyzed chemical reaction, shown below:
7,8-dihydroneopterin 3'-triphosphate + H2O -> 6-carboxy-5,6,7,8-tetrahydropterin + acetaldehyde + triphosphate
Escherichia coli (or E.coli) QueD catalyzes this reaction. CPH4 is produced in the body and is needed for formation of tetrahydrobiopterin, which is a cofactor of aromatic amino acid hydroxylase.
However, the chemical does not have the effect that was shown in the movie. It does not have any neurological effects, let alone an ability to enhance our brain powers. Thus, we still have to treat the movie as science fiction and not have any hopes of raising our brain power exponentially. At least not yet.
Hope this helps.