Can you place two boost converters in series to boost 3v to 180v?
A single stage boost converter from 3v to 180v would be very challenging, too large a ratio for the compromise design of the boost inductor. 

However, a single stage flyback would be straightforward.

An alternative two stage design that is very robust, would be an initial push-pull inverter to an intermediate AC voltage, followed by a Cockcroft Walton multiplier.