Low duty cycle 12VDC to 120VAC inverter
If your motor can tolerate a square wave, it is fairly easy to create a push-pull driver connected to a center-tapped transformer. You can use a transformer normally used for step-down reversed as a step-up. 

I successfully drove my telescope synchronous motor with a DIY circuit as I described. Sorry, I don't know where the schematic is. 

Edit: Here is a circuit that will create a modified square wave (less harmonics, better than what I built). This is untested, you shouldn't attempt this unless you have some experience.







simulate this circuit &ndash; Schematic created using CircuitLab

The output should look like this: