||Short answer: No.|
Long answer: While there may be some long, complicated, and convoluted method, I'm not able to imagine a feasible synthesis for GHB from propylene glycol. It is missing a carbon (gamma-hydroxybutyrate--butyl being 4 carbons, propyl being 3 carbons), and you would have to remove the secondary alcohol and add another primary alcohol after adding the additional carbon. Then you would get 1,4-butanediol, which is a relative of GHB, but not strictly a precursor. And remember, unless you are an experienced chemist, venturing away from established procedures is very unwise. Even with established procedures, one should be extremely cautious and learn as much as possible before attempting any kind of kitchen chemistry.