There are other methods of doing this.
The CuSO4.5H2O supplies water for the oxidation, and may also somehow mediate the oxidation.
I recommend trying some kind of halogen-based oxidation. TCCA is the ever-popular agent for this. There's threads on the topic. Basically, doing an acidic oxidation should work, as halogen is the real oxidizing agent. Much room for research in this area.
Failing that, I could look something up for you. I have a couple papers involving this sort of oxidation.