Hi,
One method would be to use an inductor and MOSFET configured in boost mode to step up the voltage to +300v or thereabouts and then use an H-bridge converter to convert this back to AC.
However, I would not recommend this as you have high peak currents, you need to use high voltage MOSFET/IGBT meaning that they will have higher Rds(on) and thus higher losses.
Are you sure you mean transformerless or not without iron core bulky transformer? The best solution would be to use a ferrite transformer at 50kHz or thereabouts to boost the voltage and then use H-bridge converter.
Hope this helps.
Tahmid.