Your schematic is a self-oscillating boost converter. It might do the job although it is likely to be unstable (erratic as in working or not woking). The load makes a big difference as to whether it operates properly. Notice that a boost converter with no load might rise to alarmingly high volt levels in a fraction of a second.
And what amount of Amperes at 12V do you desire? Then you must input 3 times that amount of Amperes at 5V. Can you be sure the C-port will give you that much current? Does it require a protocol known as enumeration?
Capacitor-operated voltage multipliers are predictable and easier to experiment with. Did you rule out that type of converter?